Dan_AA,
To actually see the new fields that you add, you will have to customize the screen and add the fields onto it.
Go to Customize > Screen and edit the CRM_EditLead screen. In the designer you should see the new fields you added on the left and you should be able to drag them onto the screen. When you go to edit the CRM_EditLead screen it will ask you to make a copy, when making that copy replace the tab links to the existing screen.
-Michael