Operating GPS on Standard Horizon HX870 VHF radio?

After 5  years, I finally broke down and bought a VHF radio but having some challenges learning to use it.
Anyone with experience inputting and removing waypoints on the HX870 or HX890 available to provide some advice?
I wanted to input waypoints for where I drop crab traps,then navigate back, delete the old ones... haven't figured out how to do that yet despite reading the manual.
Thanks in advance.

Check this link out
https://groups.io/g/hx870-hx890/topic/76230558

Hope it helps