Desperately Needed Ranking System

Hello,
I would like to ask a question if i dont bother you… I am just a beginner and i am trying to do some advance things (for my abilities)… Whatever, the system that i m thinking is like that;

  • First of all i need a ranking system. My users must have some xp points that they won or gain from some activities (like daily visit, commets, advertisement click etc…)
  • I will open some contest for my users
  • Users have to give some of their points to join the contest as an enterence fee
  • Limited number of users can join contests so script need to be automatic on this part.
  • If they win, they will get some extra points
  • After collecting points they might spend their points on website reedemtions, gifts or joining other contests…
  • Rewarding users with points dont need to be fully automatic system. I can give the points by myself but as i said, spending points need to be automatic.

As i said beginnig of my message, i am a complete rookie… I need this system, however i dont have any single idea about where i should start. Can you give me some advices? And if someone interests to create it for me, i can hear your price offer