It needs to be an IMG, the code should start [ img]http
When I got mine I just right clicked on the sticker in a post and copied image location, then put the [img in front and[/img behind it and changed state abbreviation and city, the miniWeather10 can be changed to the sticker you want as well look at weather underground stickers and change the name to which one you want
[ img]http://http://weathersticker.wunderground.com/weathersticker/miniWeather10/language/www/US/WI/Berlin.gif[/img ]
Take the spaces out between the [] and it should work