In order for people to access your map they need to have the exported map file. Since you know how to use MediaFire, Put the exported files into a .zip folder, then upload it to Mediafire. After that, give the people you want to have the map the Download link that mediafire gives you so they can download it. After they download your map the need to extract the files into the "exports" folder, and that should do it.
Note: Make sure you put a Portal (under the MAP tab in mapmaker)in your map or they won't get it in.