This is my vf page
<apex:page controller="MailBouncedController"  sidebar="false" Showheader="false" id="pg">
    <!-- Import Necessary Jquery js File and StyleSheets-->
    <apex:includeScript value="{!URLFOR($Resource.jQuery, 'js/jquery-1.6.2.min.js')}"/>
    <apex:includeScript value="{!URLFOR($Resource.jQuery, 'js/jquery-ui-1.8.16.custom.min.js')}"/>
    <apex:includeScript value="{!URLFOR($Resource.jqPlugin, '/jquery.blockUI.js')}"/>
    <apex:stylesheet value="{!URLFOR($Resource.jQuery, 'css/ui-lightness/jquery-ui-1.8.16.custom.css')}"/>
                    <script>
                function selectRecord(a,b)
                {                                     
                    window.opener.SetDonor(a,b);              
                    window.close();
                }
                function Exit()
                {
                    window.close();
                }             
            </script>
            <apex:pagemessages />
            <apex:form >
                <apex:pageblock >
                <apex:pageblockbuttons location="bottom">                     
                        <apex:commandbutton value="Exit" onclick="Exit();"/>
                    </apex:pageblockbuttons>
                    <apex:pageblockSection >
                        <apex:pageblockSectionItem >                  
                               <apex:outputpanel >
                                <apex:inputtext value="{!Searchstring}" style="width:130px"/>
                                <apex:commandbutton value="Search" action="{!SearchDonor}"/>
                             </apex:outputpanel>
                         </apex:pageblockSectionItem>
                     </apex:pageblockSection>
                     <apex:pageblockSection title="Contacts">
                    <apex:pageblocktable value="{!ConList}" var="Con" > <!--  rendered="{!ConList.size>1}" -->
                            <apex:column headervalue="{!$ObjectType.Contact.fields.Contact_ID__c.Label}">
            <!--       <apex:outputlink value="#" onclick="selectRecord('{!Con.Id}','Contact')">{!Con.Contact_ID__c}</apex:outputlink>
            -->       </apex:column>
          
                            <apex:column headerValue="Name">
                                    <apex:outputText value="{!Con.FirstName}"/>
                            </apex:column>
                          
                            <apex:column headerValue="LastName">
                                <apex:outputText value="{!Con.LastName}"/>
                            </apex:column>
                          
                            <apex:column headerValue="House No">
                                <apex:outputText value="{!Con.House_No__c}"/>
                            </apex:column>
                          
                            <apex:column headerValue="Building">
                                <apex:outputText value="{!Con.Sub_Building__c}"/>
                            </apex:column>
                          
                            <apex:column headerValue="Street" width="200%">
                                <apex:outputText value="{!Con.Street__c}"/>
                            </apex:column>
                          
                            <apex:column headerValue="Mailing City">
                                <apex:outputText value="{!Con.MailingCity}"/>
                            </apex:column>
                          
                            <apex:column headerValue="Post Code">
                                <apex:outputText value="{!Con.MailingPostalCode}"/>
                            </apex:column>
                          
                            <apex:column headerValue="State">
                                <apex:outputText value="{!Con.MailingState}"/>
                            </apex:column>
                          
                            <apex:column headerValue="Country">
                                <apex:outputText value="{!Con.MailingCountry}"/>
                            </apex:column>
                          
                     </apex:pageblocktable>
<!--                        <apex:outputpanel rendered="{!ConList.size==0}">
                            No records to display
                         </apex:outputpanel>
-->                     </apex:pageblockSection>     
                </apex:pageblock>
            </apex:form>
            
</apex:page>

and this is my controller...
public with sharing class MailBouncedController {

   // public String ConList {get; set;}
    public List<Contact> ConList {get; private set;}
    public string SearchString {get;set;}
    public string DonorName {get;set;}
    public string DonorAddress {get;set;}
    public Contact Donor {get;set;}
    public boolean showPopup {get; set;}
  
    public MailBouncedController(){
       //DonorName = 'Mr Syed Bilal Ali';
       //DonorAddress = '45 Bulding Sub Building Street London E17 8EN'; 
       Donor = new Contact();
    }
  
    public PageReference SearchDonor(){
        // List<Contact> ConList = new List<Contact>();
       // ConList = new List<Contact>();
        string s = SearchString + '*';
        try {
        List<List <sObject>> searchList = [FIND :s IN ALL FIELDS RETURNING  Contact(Id,Contact_ID__c,Account.Name,Email2__c,Email3__c,OtherPhone,Organisation__c,Street__c,
                                            Account_Number_2__c,Account_Number_1__c,MailingCountryCode,Building_Name__c,AccountId,IsPersonAccount,Sub_Building__c,Locality__c,
                                            House_No__c,Email,Salutation,MobilePhone,Phone,Firstname,LastName,MailingStreet,MailingCity,MailingPostalCode,MailingState,
                                            MailingCountry, AssistantName,AssistantPhone,Secondary_Email__c,Secondary_Last_Name__c,Secondary_Middle_Name__c,Prefix2__c )];
    
      
         ConList  =  ((List<contact>)searchList[0]);
         // system.debug(searchlist.size());
        //return null;
        if(ConList.size() > 1 )
                        {
                            showPopup = true;
                        }
            //return null;                    
       else if ( conList.size() == 1 ){
       DonorName = ConList[0].FirstName;
       DonorAddress = ConList[0].MailingStreet + ConList[0].MailingCity;
       showPopup = false;
                            
       }
      
       else if ( conList.size() == 0 ){
       apexpages.addMessage(new Apexpages.Message(apexpages.SEVERITY.info,'No matches found ! Try again'));
       showPopup = false;
                        }              

        }
      catch(Exception ex){
                       showPopup = false;
                       ApexPages.addMessages(ex);
                 }  
                  return null;
    }
  
}