Those starts under your name change with how many posts you have.
Dont just post to get more stars, thats not the point of the forum.
To get pics in your sig, use forum code:
[img] url to image, like: http://site.com/pic.gif [/img]
But read the rules first
As for Karma, you must have atleast 25 posts to use it, once you have 25 posts you can Applaud or Smite any user who has atleast 25 posts.
If you applaud someone the karma number goes up, if you smite someone it goes down.