<apex:page standardController="Campaign" recordSetVar="contacts" extensions="Campaign1">
    
    <apex:form >
    <apex:pageBlock title="Campaign Search">
            <h2>Name : </h2>
            <apex:inputText label="SearchName" value="{!searchName}"/>
            <apex:commandButton value="Search" action="{!searchbox}"> </apex:commandButton>
    </apex:pageBlock>
    
    <apex:pageBlock title="Campaign Detail">
        
    </apex:pageBlock>
    
        <apex:pageBlock title="Contacts List" id="contacts_list">
            <apex:pageBlockTable value="{! campaigns}" var="ct">
                <apex:column value="{! ct.Name }"/>
                <apex:column value="{! ct.Type }"/>
            </apex:pageBlockTable>
<table style="width: 100%"><tr>
    <td>
       Page: <apex:outputText value=" {!PageNumber} of {! CEILING(ResultSize / PageSize) }"/>
    </td>            
    <td align="center">
<apex:commandLink action="{! Previous }" value="« Previous"
     rendered="{! HasPrevious }"/>
<apex:outputText style="color: #ccc;" value="« Previous"
     rendered="{! NOT(HasPrevious) }"/>
&nbsp;&nbsp;  
<apex:commandLink action="{! Next }" value="Next »"
     rendered="{! HasNext }"/>
<apex:outputText style="color: #ccc;" value="Next »"
     rendered="{! NOT(HasNext) }"/>
    </td>
    
    <td align="right">
        Records per page:
<apex:selectList value="{! PageSize }" size="1" >
    <apex:selectOption itemValue="5" itemLabel="5"/>
    <apex:selectOption itemValue="20" itemLabel="20"/>
    <apex:actionSupport event="onchange" reRender="contacts_list"/>
</apex:selectList>
    </td>
</tr></table>
        </apex:pageBlock>
    </apex:form>
</apex:page>

public class Campaign1 {

    public Campaign1(ApexPages.StandardSetController controller) {

    }


 public string searchName {get;set;}
 public list < Campaign> campaigns{get;set;}
 public Campaign c {get;set;}
   
   
   
   
 public Campaign1(apexPages.standardController con) {
 c = (Campaign)con.getRecord();
  campaigns= new list <Campaign> ();
  campaigns= [select ID, Name, StartDate, EndDate, Type from Campaign];
 }
 
 
 
 
 
 
 public void searchbox() {
  campaigns= new list <Campaign> ();
  String name = '%' + searchName + '%';
  campaigns= [select ID, Name, StartDate, EndDate, Type from Campaign where Name Like :name];
 }
 
 
 
}