Making a template thumbnail
I am on windows.
I hit the print screen button. This puts the entire desktop into the clipboard as a huge @ss image. For me it is 3160 x 1050 since it grabs the entire desktop.
I pull this into paint.net and crop, then resize it to the image size of the theme thumbnail, which I don't know off of the top of my head. maybe 120 x 90? Save it as a png named "thumbnail" put it in the directory and you are done.
2.Use the print screen button and it takes a screen snap of your desktop
3.No go and start your favorite image editor and right click and paste ( it should paste the screen snap )
4. Resize it as you like it ( make it 120 x 90 )
5. Save it as thumbnail.png
6. Put it in your theme's directory :)
Thats all :)