Let's start with this:

http://i145.photobucket.com/albums/r230/flashingflash/cloud1.jpg
Draw a simple brushed cloud, I sugest the 2nd brush.

http://i145.photobucket.com/albums/r230/flashingflash/cloud12.jpg
Next, make a filling with the brush, like that, and colour it inside:

http://i145.photobucket.com/albums/r230/flashingflash/cloud123.jpg
Okay, fill the left part *not the grey part* with [SIZE="4"]white[/SIZE]

http://i145.photobucket.com/albums/r230/flashingflash/cloud1234.jpg
It should look like this.
___
Let's start with the Filters part

http://i145.photobucket.com/albums/r230/flashingflash/cloud12345.jpg
Select all the image, and press F8. Here, see it.
You just transformed the image in a Movie Clip (MC).

http://i145.photobucket.com/albums/r230/flashingflash/cloud123456.jpg
Now go down to the Filters menu.

http://i145.photobucket.com/albums/r230/flashingflash/cloud1234567.jpg
Put this in, after you selected Blur, from the effects.
____
In the end, you can do what you feel like with them!
I made this:

Good Luck!
-Wtf
