How to upload image in signature

I've passed the winners line for NaNoWriMo and want to upload a GIF winner image rather than use the one I have now which is linked to their server.

I feel like an idiot, but I couldn't copy and paste their GIF image into my signature. The only option I saw was Insert Image on the menu. When I did that, it wanted a URL, but the image is on my C drive.

I looked in the AW FAQs and did a search of the forums, but didn't pull up anything that told me how to insert this image.

I know this must be really simple. Your advice is appreciated.

Thank you, Smiley. That explains everything!

I thought there would be a way to upload it from my C drive like a custom avatar.

I''ve thought about putting pictures on my blog and I suspect I'll have to do something similar so I appreciate getting the prod to learn a bit more about technology.

Thanks, again!