Palm Treo 755p

I just got my new Treo 755 so i'm first learning everything about it. I have a ringtone i downloaded on my phone but it only plays in the p tunes after i download and save. How do i convert it to ringtones. I was told by someone else when the song plays i should pause it and then save it as a voice memo, but it doesn't show up there either. Any ideas from anyone.