Welcome to MobileRead, leemacmorris
Elfwreck gave you a few good places to get started on.
Also the blue bar up on top has a link to the thousands of free ebooks beautifully formatted by some of the very dedicated members on MR. I think the kindle format is the prc (which is listed as mobipocket). I believe you should download the mobipocket download guide also.
At the very top of the page is the link for our Wiki.
Here is the how to page for the kindle
/wiki/Kindle_HowTo:_File_Conversion
Jump in an ask questions and someone will chime in and answer / or point you to a thread with information.