help creating maps with waypoints

[galenweaver]

I go rafting and want to create maps with waypoints representing the camping sites and rapids.

I then want to download these as GPX files so that I can follow my progress down river on my phone with Backcountry navigater or viewranger.

I know the programs will load GPX files but I want to create the maps on my computer and add the waypoints with descriptions my my computer as well then download them.

Anyone have advice of the best way to do this.

Thanks,
Galen