Software for adding extra areas to existing maps?
I'm no practised dungeon mapper. I'm looking to add some areas to existing old school maps like the following:
This is the player map, and I have the GM version with extra, secret areas. I want to add those extra areas but without the map keys and notations. This is to use in Foundry VTT, if that matters. Any suggestion as to a decent program I can use for this?