Rotor button is inside the cap. You can't miss it.
Google is your freind. Here's a link how to change the cap and rotor.
This link is a sample. Match up the pics on it to see if this is what your motor looks like.
Anything you need to find "HOW TO" do just google HOW TO_______
How to Replace a Distributor Cap and Rotor - Yahoo! Voices - voices.yahoo.com