nice ride taff, at the top of the page just under the ub banner you will see a row of buttons,
Forums Home User CP FAQ Members List Calendar New Posts Search Quick Links Log Out
use the third button " user cp" that is user control panel.
goto the control panel and use the "edit signature" button, then upload your pic from your pc or "photobucket" or whatever you use to host your pics, make sure you adhere to the site rules regarding size of signature. just holler if you need more help.