I gotta be at work soon, but I'll try to remember to post a lesson about "rests" (and other notations) as soon as I can. For a quickie lesson, without pictures, here's a brief explanation about some rests for you.

A rest indicates that a silence will be heard for a specific amount of time (depending on which rest is used).

There are the following types of rests:

Whole note
Half note
Quarter note
Eighth note
Sixteenth note
Thirty-second note
Sixty-fourth note
Double whole note

I'll do my best to remember to post a lesson going into detail on these at some point (no time to do so now though).