Hi sandy,

   Hope you dont mind  left panel made by <apex:outputPanel /  html <div> tag . I a have a  simple solution for you which is using Html <DIV> tag ,if you use <apex:outputPanel> it will be little more difficult to make left box/panel. Here is the visual force markup;

<apex:page sidebar="false" showHeader="false" controller="MyTestController">
        <apex:form >     
              <div style="width:150px;height:600px;border:solid 1px red;background-color:#C0C0C0;float:left">
                  <apex:commandLink action="{!clickme}" value="Click Me"/>
              </div>
              <apex:outputPanel style="width:150px;border:solid 1px red;float:left;background-color:#707070">
                 <apex:outputText style="color:white" value="{!clicked}"/>
             </apex:outputPanel>
        </apex:form>
   </apex:page>

Here  is the apex class to process the Click Me  link .

public class MyTestController
{ 
  Public String clicked{get; set;}
  
  public MyTestController()
  {
    clicked='Yo have not Clicked';
   
  }

  public Pagereference clickme()
  {
    clicked='Yes Yo have Clicked the Apex Command Link !!';
    
    return null;
  }

}

  While the page loads the constructor  MyTestController()  will load and set the Clicked string  variable to not clicked.The method clickme() is executed when you click the click me link. In the clickme() method you will set  Clicked string    variable  as  'Yes Yo have Clicked the Apex Command Link !!'.  This is chemestry of apex class and visual force page.

Hope you understood ..

Feel free  for further clarification.