Once you have registered yourself, you will see that that a new menu item "My teams" appears to the left. This allows you to create one or more teams to take part in the event.
From this menu you can create a team, start entering names, change it to suit circumstances and so on. You don't need to get it complete, or even right, first time. You can come back time and again and change it as you like. There is a deadline: we will freeze the team lists 3 weeks before the event (21st February 2014).