Can you import songs to your music on an iPhone or the computer?

I want to buy GarageBand to make songs but I don't know if you can save them to your music app or your computer iTunes. Can you?

Yes of course you can, after you finish creating the song, just drag the file into to itunes and you should be all set! If you do not want to drag it from the desktop and just drop it into the itunes window in itunes go to file -> import and select your file!