[url=http://www.lightningmaps.org/blitzortung/europe/index.php?bo_page=statistics&bo_show=station&bo_sid=970&bo_page=statistics&bo_show=station&bo_sid=970]Statistics of Blitzortung station Walsall,West Midlands[/url]
The simplest way would be to copy and paste my code from above into your signature replacing the text (I've now high lighted in red) to what ever you want people to see, or leave as is.
Here's a shorter example of above for reference.
[url=http://someurl.com]my_text[/url]