I have my main computer (desktop) and my laptop and my Iphone all set up under the same itunes account. I cannot figure out how to get music that I purchased on my iphone to my desktop or laptop! I have homesharing on! It's very frustrating!

I have home share turned on and have a desktop for the main acct and a laptop and an I-phone. I purchased music on my Iphone and can't figure out how to get it onto move the desktop or laptop. It's very frustrating because I don't understand some of the I-tunes terminology and I have read through it all and did what sounds right but still no success!! Grrrrr.....I feel like I need someone to walk me through it!