At risk of showing how much I suck at UI, I can't get a link to work to point to a detail page.

This VF page only shows if there's an error, and I want to show a link to a Chatter Group for some of the errors (let's assume all the time for this thread).

How do I do that?

If I try to pass the ID from a method to a class var, I get an error "Variable doesn't exist: newGroup"

VF:

<apex:page standardController="Opportunity" extensions="createExternalGroupController" action="{!createExternalGroup}">
    <apex:pagemessages />

    <apex:form>

        <apex:pageBlock id="thePageBlock">

                <apex:commandLink id="groupExists" value="Go to Customer Group"  action="{!groupLink}"/>
        </apex:pageBlock>
    </apex:form>
</apex:page>

 Apex:

public with sharing class createExternalGroupController{

    public final Opportunity o;
    public PageReference pageRedirect= new PageReference('');
    public Id newGroup;
    public createExternalGroupController(ApexPages.StandardController controller) {
        this.o=(Opportunity)controller.getRecord();
        pageRedirect=ApexPages.CurrentPage();
    }
    
    public pageReference groupLink(){
        PageReference pageRef=new PageReference('/'+newGroup);
        return pageRef;
    }//opptyLink

    public pageReference methodThatDoesStuff(){
       CollaborationGroup g=new CollaborationGroup();
                g.CollaborationType='Private';
                g.CanHaveGuests=TRUE;
                g.name=groupName;
       insert g;

       newGroup=g.Id;
       return pageRedirect;
    }