If you mean you want a signature at the end of each of your posts, then here you go:
If you have a picture saved on your computer, then go to http://www.imageshack.us
Once there, click on the 'Browse' button, you can then look through your folders to get the pic you want.
Once you have got the picture, press 'ok'. Now click 'Host it' You will be taken to a page where your picture will be.
Putting the picture in you sig
Copy the image URL (right click, copy image)
Click on 'My Controls' on TheRugbyForum and then click on 'Edit Signature'.
Either click on the 'IMG' button, or type in .
Then paste your image location.
Finally press the 'IMG' button or type to close the tag and click on 'Update my Signature'
If you meant uploading a pic in general, the it's the same thing only you put the pic in your reply rather than sig.