SIG help

[The Eternal]

What Are the Regulations For Sigs, I was going to make one in PhotoShop but realized i don't know the rules for sigs on this(or any) forum. Any help would be great

[Civilian]

The must be no bigger than 400x300 and can't include anything offensive. ;)

[Marsman]

And no larger than 40kb in size also. :)