Users accumulate points from each event that they attend. To set the points gained for an event, see Create a new event (and you can also edit the event to change the points.) By default, each event will earn the attendee one point.
You may wish to give an attendee more (or less!) points. See Add and remove attendees for instructions on how to get to the following popup.
The user must be marked as attending. Then, click on the ‘Extra’ tab.
Change the number of points to the desired value, and it will be automatically saved.