How to transfer music from mp3 to itunes?

I need to know how to transfer my music from my mp3 downloader onto my music app on my iphone. I have the normal music app but I don't know how to transfer my mp3 music onto that app because it seems like I could only transfer itunes music to it. Someone please tell me how to! D

Thats easy, just add the mp3 into your list: http://www.justtext.com/messageboards/20131130182607.html