Set Waypoints

I have a Quatix 7 Pro. I want to create a custom waypoint by entering its GPS coordinates and then be able to navigate to it. I have the GPS coordinates a pair of numbers -- I do not want to use a map or a search engine or stand at the location. How do I do this? And once I have done this, how do I look at the list of custom waypoints and rename them or delete them? I cannot find an interface to do this either on the watch or in the Garmin Connect App, nor does the manual appear to cover this.