iPod MP3 songs not transfering from iTouch to new iMac

Well I just got my new iMac this morning, everything perfect!

Anyway I have some songs that are in MP3 format. and some videos that I converted myself to an iPod supported format. Well when I sync all it syncs are just my iTunes purchased music. I tried just simply dragging and dropping them into iTunes but it will not work, so how do I put the other songs and videos into iTunes on my new Mac
Also, I did authorize my new machine.

New to OS X sorry if its a dumb question.

I am trying that but these songs are not on this mac, just on my iTouch, I want to get these MP3 songs from my iTouch to my Mac, could I somehow enable the disk space on my iTouch and copy and paste?

Thanks for the help!

okay, I just got off the phone with an Apple representative and they said that the only way of doing this is by using a 3rd party software that they do not recommend.

thanks for your help!