You can create your own event by clicking on the Events tab and submitting a new event. You will need to include as much information as possible about the venue, and then submit the event. This will automatically register you for the event, as well as add it to your profile Events tab.

The other option that you have is to find an event that you would like to attend, and to check the box at the bottom that says "I will attend this event." and click the "Register" button. You can go through this exact process in reverse to unregister from the event.

The last way that you can use the Events portion of the site is through the groups. You can go to a group and submit a new event by clicking on the "Group Events" link on the Group Page. Then go through the event submission process as usual, but choosing your group as the category from the drop down box.