Hello Darliene321!

Here are some helpful support articles to help you on your way to enjoying your music across all of your devices with iTunes.  In the future, I would recommend you state what kind of computer operating system (like a Mac or Windows PC version such as OS X Lion or Windows 7 etc.) you are using just to help the community pinpoint the best support option for your needs.  It would also help everyone to know which version of iTunes you currently have... the latest is the best for you (iTunes ver. 10.6 http://www.apple.com/itunes/ !)!  Also let us know if you have previous experience or how experienced you are with your devices.

Enjoy!!

iTunes: How to move your music to a new computer

http://support.apple.com/kb/HT4527

iTunes: How to re-create your iTunes library and playlists 

http://support.apple.com/kb/HT1451

iTunes: What are the iTunes library files?

http://support.apple.com/kb/HT1660

iOS: How to transfer or sync content to your computer

(iPhone) http://support.apple.com/kb/HT1296