If you click on "settings" in the top heading bar (on the right hand side)
you see a screen showing a number of interesting things like subscribed threads, latest rep received and latest rep given...
down the left hand side there is a list of settings that you can edit and "edit signature" is among those...
Click on that and the screens come up that enable you to paste code in which covers things like our tickers or upload a picture - which can be useful if you want a team banner...
If you want a literal (like you currently have your name) or a link to your diary - you put it among your code...
You can preview it until you are happy with it and then save it to lock it in...