How to download music onto my iPhone for free?

I really don't want to waste money on songs i probably won't like in a couple months. Is there a website/app that I can download any song for free on the actual app on my iPhone for music, that will download the song picture(whatever its called) as well?

There isn't an app, however what you CAN do, its first go to youtube and find some of your favorite songs. Next, get the links and put them in this: http://www.listentoyoutube.com/, this will change the videos into song files. Save these files onto your computer somewhere where you can find them, next drag and drop them into itunes, where they will show up in your music library. After that, connect your phone to the computer. Then drag and drop the files from the music library onto your phone. Check your phone, the music you got from youtube should now be there