How do I enter coordinates to navigate to?

The only way to go to a particular coordinate is to create a waypoint first, and then edit the waypoint properties and modify the coordinates.

It does not matter where the waypoint you create is located, as we will be changing it anyway.

So go ahead and create a waypoint at your current location. View the waypoint details.

Then, tap the waypoint, and tap

Edit/Reposition on Android 

or

Move Waypoint on iOS

edit it, and enter your coordinate. Save the waypoint.

The waypoint will change position to the new location once you have saved it.

Once you have entered your desired coordinate, you can then go to that waypoint' location.