Laola, I noticed that you used Microsoft paint to create the signature image. I'm assuming that means that you saved it as a bmp file, which is not good for Internet use due to the large file sizes. I'd either save the image as a jpg in Paint or find a program that will let you convert the file from bmp to jpg (as the quality that Paint saves jpgs at is, well, not fantastic).
if it doesn't work attach the picture and i'll save it to my computer and upload it then give you the IMG. And to save it as a different type, just open the pic, go to 'Save As' and save it as you normally would, although change the file type. Do what sear said, make it a jpeg file, although i save everything as PNGs.
Ok, create an account at www.photobucket.com , then click on the "upload" button and chose that file. Then Photobucket should give you a link to it (underneath it, there will be 3 in fact, highlight the one that says [img] copy and paste it). Then goto your signiature and paste that. If that doesn't work or you don't understand all of it send me a PM and I'll try and help.