Lol, that's what other members are around for- you can always ask first, and do stuff once you are certain about what to do.
Generally what you do is after you create your image is to upload it to an image hosting service such as
Imagesack or
Tinypic. Using those, you have your image already on the web, and you simply use its URL is a [img] tag to display your signature.
As an example, my signature is using imageshack - just right click and select "open image in new tab" to see the full URL of my signature.