Well, first you have to create/edit your signature. For that you can click on the "user cp" link usually on the top left corner of every page (depends on the theme you're using). You'll find the "your signature" link there.
Now you must add some code in your signature which'd include the userbars in it. If the userbar is a single image, you just have to open the image with your browser and copy its url. Now add the url in your signature (it should start with http://. Now add [img] before the "http" and add [/img] after the whole url. It should now appear as the image instead of text.
If the userbar you're trying to add uses complex scripts (like some userbars made by me), it's actually easier to add them. You just copy the text that is below the userbar in the club's original post (in a box that has "code" written on it). Just add that text in your signature without any modifications and you're done!
You can also use multiple userbars and images. Just add the corresponding text and seperate them with line breaks.
Do let me know if you're still having difficulties .