hi Tay
This is the wrong place, this is for new users to introduce themselves. User2user Tech Support is probably the appropriate spot for this question, but no point in changing it now.
Reputation is given when you like someones post. In the top right corner is a button that says 'REP'. Clicking on it brings up a box to type in to leave a message. Now with the new 'Like' button i don't see the rep button used often anymore though. Reputation power just shows others how much rep you have earned. I believe when it was first put in they had a remove rep option as well, but that got taken out eventually.
In order to check any current rep you have obtained click the 'Control Panel' in the top left. But it only shows about the last 7 reps you got, anything more stops being shown in that list, but it does stay in your rep power.