One of the first quilts I made had a ruffle. I used the "birthing" method for the quilt so that the ruffle faced inwards, I sewed the edges of the quilt around all 4 sides, leaving a 12" opening, then turned the entire thing inside out. As for the actual ruffle, the fastest method is always to zig-zag over a length of yarn and then just pulling it to the length you need, ruffling along the way.