When you track a ride and save it, it is saved under your "Completed" tab on your profile. This is also true for rides you've imported from a GPS device and marked them as "completed".
To find routes you've saved on Ride Spot, click on the "Routes" tab in your profile.
You can use these to plan rides and then navigate them, either on the Ride Spot App or by exporting them to your preferred GPS device.
Anytime you find a route you'd like to ride in the future, you can tap SAVE. Whenever you join an Event or Challenge, you will also see that the route is automatically added to your saved routes.