Welcome to MobileRead, Kahlolily
When you say "they are on my pc" do you mean you downloaded them to Kindle4PC?
You need to go back to your account, sign in, go to your kindle content, and download the book directly to your kindle....
Here's a page you might find helpful.
http://www.amazon.com/gp/help/custom...deId=200503360
You can even download the users guide and 'read along'...