I just updated my maps today. On my 2013 Melbourne 28f, I found the Clarion NP401 GPS behind a black trim panel on the passenger side, under and to the side of the glove compartment. You will will need to do three things: 1) Remove the Micro SD Card from the GPS (you will need to remove 2 little screws and plate to get to it) 2) Insert that Micro SD card on your Windows computer card reader (you will probably need an adapter) 3) Download the www.naviextras.com
Toolbox software. When you run the software, it should identify the card as the device. You will then be able to elect the maps that you want to download. A couple of hours download time/installation in our case. You will then place the Micro SD card on the GPS and you are good to go. Also, dont forget to backup the data on the Micro SD card before and after the update before you put it back on the GPS. By the way, always verify that the update is not free to Clarion customers before buying the update, as I think I paid for a map that was supposed to be free.
Note: I found the GPS unit "lose" behind the trim cover, as they only used 2 sided adhesive tape to attach it to the metal plate, so I had to do some "engineering" to make it more secure.