need to add " previous and next" buttons and display only 10 records per page

this is the apex controller i have written

public class popupExt {
    public string accId {get;set;}
    Public contact popUpAcc  {get; set;}     
    public boolean displayPopup {get; set;} 
    public List<Account> lstAccount;
    public Integer countTotalRecords{get;set;}
    public Integer offSetSize = 0;
    public Integer QueryLimit = 10;
     
    
    public popupExt(ApexPages.StandardSetController  stdController) {
    }
    
    public void closePopup() {        
        displayPopup = false;     
    }     
    
    public void showPopup() {        
        displayPopup = true; 
       
        popUpAcc = [SELECT Id, Name, Phone, Email FROM Contact where id =: accId ];
        
    }
        public void SoqlPaginationOffsetController(){
        lstAccount = new List<Account>();
        countTotalRecords = [SELECT count() FROM Account];
    } 
    public List<Account> getAccounts(){
        lstAccount = [SELECT Id, Name, Phone FROM Account ORDER BY Name LIMIT :QueryLimit OFFSET :offSetSize];
        return lstAccount;
    }
    
    public boolean getprv(){
        if(offSetSize > 0)
            return false;
        else
            return true;
    }
    
    public boolean getnxt(){
        if(offSetSize + queryLimit < CountTotalRecords)
            return false;
        else
            return true;
    }
    
    public PageReference nextbtn(){
        offSetSize += queryLimit ;
        return null;
    }
    
    public PageReference prvbtn(){
        offSetSize -= queryLimit ;
        return null;
    }
    
    public PageReference fstbtn(){
        offSetSize = 0;
        return null;
    }
    
    public PageReference endbtn(){
        offSetSize = countTotalRecords - math.mod(countTotalRecords,queryLimit);
        return null;
    }
    
  }

VF page

<apex:page standardController="Account" extensions="popupExt" recordSetVar="accnt" tabStyle="Account"  >  
  
    <apex:form >
        <apex:outputPanel id="tstpopup">
            <apex:outputPanel styleClass="popupBackground" layout="block" rendered="{!displaypopup}"/>
            <apex:outputPanel styleClass="custPopup" layout="block" rendered="{!displaypopup}">
                    <p>Account Name : {!popUpAcc.Name}</p>
                    <p>Phone : {!popUpAcc.Phone}</p>
                <apex:commandButton value="ok" action="{!closePopup}" rerender="tstpopup"/>
            </apex:outputPanel>
        </apex:outputPanel>
 
        <apex:pageBlock title="Accounts" >
             <apex:pageBlockTable value="{!accnt}" var="ac" >
                <apex:column id="two">
                    <apex:commandButton title="{!ac.id}" value="Click" action="{!showPopup}" rerender="tstpopup">
                        <apex:param name="accId" value="{!ac.id}" assignTo="{!accId}"/>
                    </apex:commandButton>
                </apex:column>
                <apex:column value="{!ac.Name}" />
                <apex:column value="{!ac.AccountNumber}" />
                <apex:column value="{!ac.Type}" />
                <apex:column value="{!ac.Rating}" />
                <apex:column value="{!ac.Phone}" />
                <apex:column value="{!ac.billingCity}" />
                <apex:column value="{!ac.billingCountry}" />
                
            </apex:pageBlockTable>
             <apex:commandButton value="First" action="{!fstbtn}" disabled="{!prv}" reRender="pt,pb" />
            <apex:commandButton value="Previous" action="{!prvbtn}" disabled="{!prv}" reRender="pt,pb" />
            <apex:commandButton value="Next" action="{!nextbtn}" disabled="{!nxt}" reRender="pt,pb" />
            <apex:commandButton value="End" action="{!endbtn}" disabled="{!nxt}" reRender="pt,pb" />
        </apex:pageBlock>
    </apex:form>
     
    <style type="text/css">
        .custPopup{
            background-color: white;
            border-width: 2px;
            border-style: solid;
            z-index: 9999;
            left: 50%;
            padding:10px;
            position: absolute;
            /* These are the 3 css properties you will need to change so the popup 
            displays in the center of the screen. First set the width. Then set 
            margin-left to negative half of what the width is. You can add 
            the height property for a fixed size pop up if you want.*/
            width: 500px;
            margin-left: -250px;
            top:100px;
        }
        .popupBackground{
            background-color:black;
            opacity: 0.20;
            filter: alpha(opacity = 20);
            position: absolute;
            width: 100%;
            height: 100%;
            top: 0;
            left: 0;
            z-index: 9998;
        }

    </style>
</apex:page>