Beginner on rails! customize store. "Agile web development"

hey all!
Uhm, dumb topic perhaps, my bad. Anyway, ive read the "How to create a
shop" in the book "agile web development". But no i'd like to add some
options to the product in the store, so the future customers can choose
ie. a bike, and then select color and size of that bike. Iv'e given
this function ALOT of taught but haven't been able to figure it out by
myself, can anyone around here please help me?

How would you do it in raw HTML? Get a book on that (you can probably
augment it with

I always Google for HTML

    site:microsoft.com html select option

When I wonder about select boxes. MS's HTML documentation is all in
one site (or three), with no popup adds or other nonsense.