This is my first tut :D. (this will be hard to do w/o photoshop)

Create your new img, 350, 125.
Make the whole background black.
Make a new layer above this one
Set your brush to white and start brushing
Set all of ur brushing to one layer (remember that the black bg is another layer and is not to be on this one.)
Duplicate your brushing layer
Set your main layer to Soften
On your duplicated layer, do Blur>Guassian Blur 13.5
Make on more layer, Filter>Render>Clouds
Set this layer to overlay.
Add your coloring adjustment layers
Add leveling or whatever else you wish.

You should get something like this
http://server2.uploadit.org/files/Bounda-xp02.jpg

ENJOY!

try making it a little more comprehendable and add screenshots, look at my tut and fm tuts

"(this will be hard to do w/o photoshop)"