How do I make these edges more natural

Hi, see the bottom of the pic? Well, how can I make these edges go up and down and be random, and seem natural?
www.ani-blade.net/Ninja.jpg

I'm assuming the edge is on it's own layer.

Try either, Filter > Blur > Motion Blur and try setting the angle to 0 and the distance to about 25.

Or try applying the ripple filter to it (in the distort drop down menu).

ocean ripple is quite good for breaking up a line like that. On a new layer, draw a white box that covers the bottom of the picture where you'd like it to be. Fill the remainder of the layer in black (It should look like an upside-down pint of guinness). Render>distort>ocean ripple (you'll have to play around with the settings, but I imagine 3,3 should be ok). And finally set the layer to "screen" blending mode.

You may want to blur it as well.

Well, that ocean ripple effect worked pretty well, but the effect went straight from one side to another. Is there a way I can keep the ocean ripple effect, but make it so some of the parts go in deeper into the image, and other parts would stick out. So basically, make it look somewhat flamy, but using the ocean ripple effect. Thanks for the help so far

try quickmasking some areas with a big soft brush before you run the filter.