I have about 900 songs on it already from the first time but my computer had to be rebooted, and when I tried to put more songs on my iPod, I couldn't. Can anybody help me? I am not good with ipods. TY

You either need to authorise your computer again.

iTunes Tutorial: Apple - iLife - Tutorials - iTunes - Authorising and Deauthorising Your Computers

Or your iPod is full up.

900 songs should be about 5gig, shouldn't be a size problem.

If there is a size problem, you have some biiig songs.