How to add songs from my Ruckus folder onto itunes?

I have the Ruckus player and I can download albums free. I also have all the songs that I downloaded onto my computer. I tried dragging the songs into itunes and it tried converting them, but it didn't work. The songs right now are in WMA format and they need to be in AAC format. If anyone could help me with this, I would really appreciate it. Thanks!!!