Hover your cursor over the 'People' tab in the navigation menu at the top of the page then in the dropdown, click on 'Online'.

If there are more than 10 people online, then click on the numerical dropdown to the right of the words 'Per page:'. Click on the number of people that are online which you would like to see on one page. If there are more people online than appears in the dropdown, select the highest number within the dropdown, then repeat the whole process again and again until you can see everyone that is online.