How to get my music off of my iPhone and on to iTunes on my computer?

I have an iPhone full of music and TV shows and a new computer. I'm trying to get my music on my iTunes on my computer. Can you tell me how? I can't figure it out.

Sign in to your apple id on your pc and you will be able to download everything you've already paid for

If you purchased all the music and tv shows from Apple, you are allowed to download them again on your computer after you sign into your account.
If you download them from other sources, you can't do that. But you can do that with the help of aiseesoft iPhone Transfer Platinum. It can help you to transfer your music, video, pics and many other things from your iPhone to your computer and iTunes. Just have a try.