Just to add some additional info for you.
Garmin Express is one of the programs you can use from your computer to up-date your built in maps, but only in some cases. Most of the time, you will use Express to create an sd card (with the new maps on it) that you will need to leave in the MFD in order to use the new maps. The reason you cant up-date the internal maps in most cases, is that the new maps are too big to fit in the mfd memory.
Homeport is also a PC based software but it is used primarily as a waypoint management, tracks, trip planning, and for viewing sonar recordings. Homeport has a lot of potential, but Garmin is not supporting Homeport any more. Actually, they have been letting it slide for years.
They really want everyone to move to Active Captain - which sucks for some things and is good at others. Active Captain is no good for trip planning and is almost useless for waypoint and track management. It also cant play back sonar recording - but Homeport mostly fails at that too.
The bad part about Active Captain is its on a phone or tablet and so not as easy to use for trip planning. Plus it just doesnt have all the tools Homeport does.
Active Captain is great for using the Helm feature - you can mirror the mfd screen on your phone or tablet and even control it from the phone. You can also record what ever is on the screen and save it on your phone. I use that feature a lot to record sidescan or Livescope/Panotics action.
It is also used to up-date your MFD software and the maps on the MFD. Unfortunately, Active Captain has a few bugs that Garmin is still working through - especially with this latest up-date and the new mapping.
Last month, I downloaded the newest version of Active Captain, and then up-dated my 7610xsv to the latest software, and bought and downloaded the newest Lakevu charts for areas I fish. When I was finished my charts were screwed up to the point marine and lake charts were completely useless. I had contour lines crossing all over the place and marine areas would go blank or grey when I zoomed in.
Im still waiting for Garmin to sort this out. They have not said whether the problems are with Active Captain, or the April software up-dates, or with the mapping itself. I suspect its some of all three.
There have been a ton of reports on different sites of issues with Active Captain, the mfd software and mapping coming from all sorts of people with all sorts of different hardware - from guys with twin 8616's with radar, autopilots, etc down to guys like us with basic setups. So far, I have not seen any pattern to the issues, so I dont know how easy its going to be for Garmin to sort this out.
I just hope it isnt long. As things stand now, I have to insert a separate sd card for my new Lakevu mapping, but I cant see any saltwater areas at all while thats in the sd card slot. If I remove it, I can see my old original Marine charts, but not the new ones I paid for last year. When I insert that sd car, I get nothing but blank maps with no detail at all other than shore line. I also have to delete all my Active Captain data of those sd cards dont work. Its a real pain.
Anyway, Active Captain is a powerful tool that works fine for most folks - but it has some some bugs and major short comings when compared to Homeport.
Oh - you do need a dedicated Active Captain sd card that stays in the mfd. If you remove it you loose all Active Captain functions - including helm.
In theory, you can use a mapping card as your Active Captain card, but in my case (and others) it isnt working at all well.
For now, I would recommend you NOT use Active Captain to up-date software on your MFD. It will probably work just fine, but there have been a number of folks having major issues.
Instead, go to this page and select the option that matches your mfd.
https://www8.garmin.com/support/software/marine.html
Then download the file that matches your MFD. Be sure to note where it goes on your computer so you can find it!
Once you have it downloaded, insert a formatted sd card into your computer - 10 gigs minimum up to 32 gigs. You can go over 32 gigs, but you need to re-format the sd card to FAT32 or it wont work. No one needs 64 gigs - 32 is way more than you will ever need.
Once the file is downloaded and the sd card is in the computer, RUN the file, and follow the prompts. This ONLY works on a PC. For a MAC/Apple you will need to jump through extra hoops, windows emulators, etc.
Once the program finishes copying all the up-dates to the sd-card, just insert it in your MFD and follow the prompts, and your all done.