<apex:page standardController="Opportunity" recordSetVar="opplist" showHeader="true" extensions="updateoppclass">
    <apex:pageMessages />
    <apex:form >
        <apex:pageBlock title="Step 1 - list of opportunities">
            <apex:pageBlockTable value="{!opplist}" var="a1">
                <apex:column value="{!a1.Name}"/>
                <apex:column value="{!a1.stagename}"/>
                <apex:column value="{!a1.Amount}"/>
                <apex:column value="{!a1.CloseDate}"/>
                <apex:column value="{!a1.probability}"/>
                <apex:column value="{!a1.Account.name}"/>
             </apex:pageBlockTable>
            
            <apex:pageblockbuttons >
                <apex:commandButton value="Cancel" onclick="return confirmCancel()"/>
                <apex:commandButton value="next" action="{!gotoVF}"/>
            </apex:pageblockbuttons>
        </apex:pageBlock>
    </apex:form>
</apex:page>

<apex:page standardController="Opportunity" extensions="displayvalues">
    <apex:form>
        <apex:pageMessages/>
        <apex:pageblock title="Step 3- enter the new value for the field:">
          value: &nbsp; <apex:inputField value="{!opportunity.Name }" required="false"/>
        <apex:pageblockbuttons>
            <apex:commandButton value="previous" action="{!gotoVF}"/>
            <apex:commandButton value="update" action="{!saveAndRedirect}"/>
            <apex:commandButton value="Cancel" action="{!cancel}"/>
        </apex:pageblockbuttons>
            </apex:pageblock>
    </apex:form>
</apex:page>

public class updateoppclass {
    
    public updateoppclass(ApexPages.StandardSetcontroller controller){
    }
    public PageReference gotoVF(){
        PageReference pref=New PageReference('/apex/Step2page');
        pref.setRedirect(True);
        return pref;
    
    }
    
}

public with sharing class displayvalues {
    public opportunity caseRecord { get; set; }
    public displayvalues(ApexPages.Standardcontroller controller){
    } 
public List<opportunity> myAccounts;
        public Boolean isEditEnabled;
    public displayvalues(){
        myAccounts = new List<opportunity>();
                isEditEnabled = false;
    }
 public List<opportunity> getMyAccounts(){
        myAccounts = [select Id,name, stagename, amount from opportunity WHERE (owner.id =: userinfo.getuserid())];           
        return myAccounts;          
    } 
    public PageReference saveAndRedirect() { 
        update myAccounts;               
        return null;   
    }
    public PageReference gotopage1(){
        PageReference pref2=New PageReference('/apex/oppupdatepage');
        pref2.setRedirect(True);
        return pref2;
    }
     public PageReference gotoVF(){
        PageReference pref=New PageReference('/apex/Step2page');
        pref.setRedirect(True);
        return pref;
    
    }
    public PageReference step3(){
        PageReference pref2=New PageReference('/apex/entervalues');
        pref2.setRedirect(True);
        return pref2;
    }
    
    public List<selectOption> oppflds;
  //  public displayvalues(){}
        public List<selectOption> getOppNames() {
            oppflds = new List<selectOption>();
            oppflds.add(new selectOption('--none--','--none--'));
            Schema.DescribeSObjectResult opp_desc = Opportunity.sObjectType.getDescribe();
            Map<String, Schema.SObjectField> opp_fields = opp_desc.fields.getMap();
            for(Schema.sObjectField fld:opp_fields.values())
            {
                    String oppfldName = String.valueOf(fld);
                    oppflds.add(new selectOption(oppfldName,oppfldName));
            }
            System.debug('stdObjectNames: ' + oppflds);
            return oppflds;
        }
}

<apex:page standardController="opportunity" extensions="displayvalues">
    <apex:form > 
        <apex:pageblock title="Step 2 - Select the field to be updated">
            <span>Fields: </span>
            <apex:selectList multiselect="false" size="1">
                <apex:selectOptions value="{!OppNames}">
                </apex:selectOptions>
            </apex:selectList>
            
            <apex:pageblockbuttons >
                <apex:commandButton value="previous" action="{!gotopage1}"/>
                <apex:commandButton value="Next" action="{!step3}"/>
                <apex:commandButton value="Cancel" action="{!cancel}"/>
            </apex:pageblockbuttons>
        </apex:pageblock>
    </apex:form>
        
</apex:page>