In the competitions module on your horses' page, the grand prix cup should appear if your horse qualifies. As with regular competitions, all you need to do is click on the symbol. It will then take you to the grand prix page for your horse to register. If your horse specialises in classical competitions, the gold cup will appear in the space between cross country and show jumping. If western, then it should appear between reining and western pleasure. Bear in mind your horse also needs to have enough energy. Divines cannot enter.

The grand prix only runs during the week.