On the witcher 3 "home page" in Galaxy there is a MORE option. Under the MORE option is supposed to be a usable GET BACK UP & EXTRAS option where i can enable the DLCs. My GET BACKUP & EXTRAS option is viewable but not highlighted or clickable like the other options. I already purchased my DLC intsaller program from the store but can not get it to work. Please help.

You don't enable it through "Get Backup & Extras" you need to click More -> Configure.
DLC will be listed under Available Content, tick the boxes next to each to install it.

Configure is the same as Backup and Extras. I can see it but it's not highlighted or clickable. The other two options - Manage and Support work fine.

Have you tried re-installing Galaxy? Sounds like there's something wrong with it.

If all else fails, download & install the DLC manually from your library:
https://www.gog.com/account

Click "Witcher 3: Wild Hunt, The" DLC Downloads will be listed towards the bottom.

Make sure you are logged in to your account in galaxy. Username at the top.

Thanks for your help . As with all Witcher/Proj Red products the bugs were on top of bugs. After uninstalling and reinstalling Galaxy It opened up enough functionality to at least get the DLC downloaded (after several attempts) and operating in game (after a couple attempts.)

The game is graphically awesome and the story is solid and engaguing, but the user interface and game controls (as with EVERY witcher release) are infuriatingly burdensome. My guess is the developers never actually played their game, only sat back at the monitor and admired it.

I have just been trying to download and install the Hearts of Stone DLC for the WItcher 3 and it has been somewhat less than straightforward, firstly after downloading the DLC once, which I left whilst I went to work ( I have a very slow connection as I live in a shared student house) It was not appearing in the installed DLC's where I assumed I would have to activate it so I just assumed it had messed up whilst I was out and not gone through setup quickly checked my downloads but couldn't see it so sownloaded again, same thing happened but I checked my GOG folders and did find the setup.exe there however it then came up with a message saying I needed a version of Witcher 3 updated to atleast 1.10, so I assume this was the reason it was not working (thanks for the explanation GOG) It is odd however that my game is not up to date as I have it toggled to automaticly update. I now must wait for the last 5 updates (10GB in total) to come through, which at 0.7MB/s is no quick process. This is the only game I have on GOG galaxy and it is a little unfair for me to judge on a samlple size of one, but if this is just how it works on GOG it is hardly user freindly. I would rather they cut all the crap on the screen gave you a list of everything downloadable for the game and a tick box for what you have downloaded and then a second tick box for what you have installed and have it actually represent those things. This is I assume one of the reasons people prefer Steam.