To edit your signature, on the top of the page there is that bar that says "User CP FAQ Calendar" etc.. Click User CP. On the left hand side of the page it says User Control Panel. Underneath that will be sections like Your Profile, Networking etc. Under settings and options it will say edit signature. Click that, and you can type in what you want for your signature. There is a toolbar similar to the one you use when you make a post or thread, and you can use that to add extra things to your signature like color, font size etc.
To edit your tanks the easiest way I know how is to go to tropicalfishkeeping.com. Its this website's parent site. At the top will be a bar with "User CP" and other things. Click Aquarium log. This will take you to a page where you can keep track of your tanks. Click Add an aquarium, and then fill in the spaces :)
Good luck, if you need any more help, just ask!
Edit: From what I can see of your tank it looks AWESOME. WAYYYYYY better than mine!
Life with Lupus is still a life worth living.
Dishing out the truth one post at a time