My ipod doesnt let me add songs unless they

Hello,
I have a 30gig ipod, i just recently received it, i know nothing about the program. I added all my music from my computer to the Itunes that I installed. The first attempts to add music were successful, exept I can only delete the music if it is in the ARTISTS: column, I added songs by themselves, but when I click on the music under the name of the Ipod, it pulls up a window with the songs that are on the ipod, but I can not delete them or anything like that. I have also noticed I can not add music unless they are in the ARTISTS column....I am sooo lost. Can anyone help me ?
Lisa