You can select a particular event using the drop down, or if you select to View Results for rider or horse, just put in a few characters of the name to get some options to choose from.
Once you have any page of results you can click on any item which is shown in red to get the results for that item - whether it be a rider, a horse or an event.
Use the date selection to give you the totals for the current year on any rider or horse page.