So I've been a good boy and am learning the modes, doing alot with intervals, and chords (like I should of years ago). So today I wrote a little riff (C maj) but just cant figure out the chords to go behind it. Is there a method to the madness.

Because of learning modes and intervals, I have been writing alot of little songs with my guitar port and Riffworks, just to help me with what I have been learning but, I am really stuck when it comes to this little riff based song. I dont want it to sound like a happy childrens song.

I can post the little song if needed but really want to know if anyone has a formula for disecting riffs and figuring out the correct chords to play.

Thanks in advance.