So, I already have a VisualForce page up, now, the thing is, i need to add an APEX class extension but unfortunately, for my account, the "Apex Classes" option under the develop menu is disabled. So how do i get this class to be attached to my webpage.


public class CoreValuesEXt
{
    ApexPages.StandardController sc;
    public boolean readonly {get; set;}
    public Core_Values__c cv {get; set;}
    public integer countEdit = 1;
    public string buttonValue {get; set;}
    public integer recordScan;
    public CoreValuesExt(ApexPages.StandardController sc)
    {
        this.sc = sc;
        cv = new Core_Values__c();
        cv.Account__c = sc.getid();
        
        readonly = true;
        buttonValue = 'Edit';
        recordScan = [SELECT COUNT() FROM Core_Values__c WHERE Account__c = :cv.Account__c];
       if (recordScan != 0){
       cv = [SELECT id, HSE__c, Professionalism_Integrity__c, Quality_Accuracy__c, Technology_Innovation__c, Timeliness__c, Value_for_money__c FROM Core_Values__c WHERE Account__c = :cv.Account__c];
        }
        
    }
    public ApexPages.PageReference Save()
    {
        return sc.Save();
    }
    
    public void ApplyAction()
    {
        countEdit++;
        Integer modolus = Math.mod(countEdit, 2);
        String total = cv.HSE__c + cv.Professionalism_Integrity__c + cv.Quality_Accuracy__c + cv.Technology_Innovation__c + cv.Value_for_Money__c + cv.Timeliness__c;
        if(modolus == 0)
        {
            readonly = false;
            buttonValue = 'Save';
        }
        else
        {
            if(total != 'nullnullnullnullnullnull')
               {
            if (recordScan == 0){
            insert cv;
            readonly = true;
            buttonValue = 'Edit';
            }
            else
            {
            update cv;
            readonly = true;
            buttonValue = 'Edit';
            }
            }
        }  
        
    }
}