Give out reputation points to other members who have made what you consider a good post or take away reputation by giving bad for a post you do not agree with.

To do this you look at the top of the post,to the right on the post you agree or disagree with.
You will see a icon like this

Click on it and you either tick "I agree" or "I disagree" and you may add a reason why if you choose.

To see if you have reputation points you go to "User Cp" and open it and you will see a listing of the points you have recieved.

Use this option wisely and fairly.