If a client has already paid for an entry outside of the system, you can manually add their entry details to your Event from your dashboard.
Navigate to Event - Event Booking in the menu on the left.
Click on Add New in the top right to add a new entry.
Now complete the entry details by selecting the Event, choose the class, and fill in the horse and rider details.
You can select whether the entry is already Paid or Unpaid and choose whether to Send Update by email to the person you are entering.
When you have finished, click the Update button in the bottom right. This entry will now be added to your Event and will appear under Event Booking.