For example, to add the Thunderforest openCycleMap map:
- Sign up with Thunderforest to get an API key.
- Goto the Thunderforest openCycleMap map page at: https://www.thunderforest.com/maps/opencyclemap.
- Copy the opencyclemap server URL that is shown on that page: https://tile.thunderforest.com/cycle/{z}/{x}/{y}.png?apikey=<apikey>. Replace <apikey> with the key you obtained when you signed up on Thunderforest.
- Go back to Trail Boss and select the + button in Trail Boss's More Maps page to add a new map. Name it 'Thunderforest Cycle'
- Paste the url that you copied from Thunderforest into the Server URL box.
- Tap the green switch beside the map name to select the map for use on Trail Boss's map page.