It's not hard to put a picture in your sig. You choose the pic that you want to put on your sig. Make sure it is small enough to fit into the Dis guidelines... i think this is 200x500 pixels. If not you can change the image size in a photo editing software like Photoshop, etc. Then you upload your picture onto the web. There are several good photo sharing websites out there for free. A lot of Dissers use photobucket.com. Then you copy and paste the link into your signature, just like you do the counters etc.
If you have any trouble, PM me and I will try to help.