I need help with the basics...

I am not knowledgeable concerning chartplotters. I have a 2014 Garmin 541s that says it comes with built in maps. I have yet to see any map except the navigational map. So I thought I would load a Bathymetric Bag chart onto the chartplotter via Homeport. I have Active Captain which I can load the bathy info onto, then transfer it to Homeport, then use a SD Card to transfer from Homeport to the 541s unit. Is there a way to unlock the map section of both Homeport and the chartplotter? I have been on this project for over two years and haven't accomplished anything. Exactly what should I do? Thank you, Bob