First, navigate to the Characters Page by using the top bar navigation. Then click on the "Create" button in the top righthand corner.
Next, fill out the Character creation page. Every section is required, but don't worry if you don't have a full idea what you want to do as you can always edit your character later. You'll notice that there are not many sections to a character at this point. The majority of the things that get attached to your character during play will occur on the game tabletop.