Okay, right click on the image, then go down on your little mini bar and click Save. Then save it in whatever file you want, and name it. Then upload it to Photobucket, or whatever you use to upload images. Then, put down
in your signature (to get there go to Settings next to Log Out and then there'll be a bar on the left side of the screen. There you'll find Edit Signature). Then, in the center of your IMG thingy, put in the home page of where you uploaded it (Example, http:/ /home.comcast.net). Then do a foreward slash and put in a ~ and after that your username of the place you uploaded the image (Example, /~cakilman). Then another foreward slash and the file you saved it in on the site you uploaded it. (Example, /pwpimages). Then another foreward slash and the file name of your picture on your computer (Example, /LotRsig.png). Most places only accept png files like I have here, but I'm not too sure. Now this is what it should look like without the IMG thingy:
http://home.comcast.net/~cakilman/pwpimages/LotRsig.png
When it has the IMG thingy around it it'll look like this: