How to get music to iPhone 4S?

I have all my music in an app called MyMedia. I don't have a lot because the download process is terrible. Is there anyway I can transfer that to my iTunes app on my phone, then transfer that to "Music"?

Also, how to get music to iTunes to then download it to my iPhone? (From my pc)

Download iTunes on your computer.

If your music is on your computer, import those files to the iTunes library.
iTunes does the rest.