I'll explain the positive rep first. For example say your rep is 100. If you leave a positive rep for someone then 10% of that 100 will be added to the member that received the feedback. So in the example of 100 you would add 10 points to someone else's rep total. How do you add rep? Look at this screen shot and look for the black arrow below my avatar:
Click on that scale looking thing.
Once you click on the the scale looking thing then this little pop-up will appear. Now since I'm using myself as the example then of course you would select the "I approve" choice. You have the option of writing a reason for the rep which is always recommended:
Now just as you have the ability to leave a positive comment for a member you can also leave a negative one if you choose. Now I personally only leave negative feedback in retaliatory circumstances. Some members will leave it for whatever reason. When you leave a negative you will then deduct points from the receiving members rep total. The amount deducted is 5%. So in the example of the 100 rep amount from above you would reduce the receiving members point total by 5 points. Here is an example of a negative rep being left for someone. Let's use Tieguy as the example
:
Taa Daa!!