You can't upload a picture to your signature the same way you can to a post. The picture has to be "on-line" somewhere, and then you can just include a link to the image URL the same way you would put an image in line with a post to a topic, by putting the image URL between [IMG] [/IMG] tagsIf you don't have any other place to post you images, you can find an old thread that you participated in, edit your post to include your desired picture file as a File Attachment, and then see what the resulting URL is and use that URL for the image in your signature.