Here's the page.

http://www.wunderground.com/stickers/

It says "Build your sticker".

There's a choice of style of "stickers". "New Stickers", "Classic Stickers" etc..

It will show "Input Location"
After you do that you click FIND
That will bring up a new page and you'll see NameofCity Weather at a Glance.
Just above that and to the right near the Facebook symbol etc, it says Get Free Weather Stickers and it says
Get more styles and options for your Weather Sticker here.

After you have built your sticker, you then need to paste the code into your Signature File which is in your User CP.

User CP
Settings and Options
Edit Signature

I recall having some difficulty with the code of mine when I first used it but I can't remember this moment why that happened or how I fixed it.

Anyway, give it a try and if you need help I think there are some posts in the Computers and Technology Forum about it or else just post here again and we can help you with it.



EDITED TO ADD.
I just tested it.

Our NT Forums can not use HTML which is the code used at wunderground.
Here is an HTML to BB or vB Code Converter.
http://www.seabreezecomputers.com/html2bbcode/

It's just a matter of clearing the box and then typing the wunderground code into the box.
Hit CONVERT
and there's your code for your Signature File