graphicxtras.com for plugins and presets
How to install Photoshop gradients in CC 2017 2015 2014 CS6 CS5 CS4 etc. Photoshop gradients are in GRD format
Select your Photoshop GRD gradients file (s) and copy
Go to the applications or program files folder (mac or pc)
Expand the Adobe / Photoshop application folder
Go to the "presets" folder
Paste or place the GRD Photoshop gradients into the "gradients" folder
Start up Photoshop
Select the gradient tool in Photoshop toolbar
Go to top of Photoshop (left) and open the presets picker 'gradients' dropdown
Access the GRD gradients via the right side menu of the gradients panel in Photoshop by name
$7.79 (also GBP, etc) per set GRD format download
$7.79 (also GBP, etc) ** 32,000 Colorful gradients GRD Gradients for Photoshop and Elements (selection)
This tutorial shows you how to install the gradients into the admin / application folder of the gradients as well as the user account folder. It also shows you how to load the gradients via the gradients presets picker load / replace commands and the edit menu equivalent. The tutorial also shows you how to open multiple gradients into Photoshop - there are also a number of links to other tutorials and free gradients
Add the GRD files to the presets 'gradients' folder in your applications / program files folder
Or Add GRD to your presets 'gradients' folders in your user account (requires no privileges)
The locations for the mac are HD/Applications/Adobe Photoshop CC 2017/Presets/Gradients (requires admin privileges)
The location for the mac and non admin privileges (user account) is ~/Library/Application Support/Adobe/Adobe Photoshop CC 2017/Presets/Gradients
The equivalent locations on the pc are "program files" folder and the "appdata" folder (in your user account). If you are still using Photoshop CS6 etc then go to the equivalent folders for the CS6 or CS5 or CS4 etc versions of the application.
If you add the preset gradient files to the user account folder, you will see the gradients appear in the right side menu but they will be separated by a line to show that they are in the user account presets section
Personally, I think it is always best to add them to the user accounts 'presets' folder.
select the gradient tool
go to the gradients panel / presets picker (top left)
go to the right side menu
select the load or replace command
browse for the gradients GRD file
You can load / replace the Photoshop gradients in most versions via the edit menu manager (edit menu) and also via the gradients panel right side menu replace (though you can also click the load command on the dialog itself). The load / replace gradients is available in a number of places such as with the gradient tool and also via the layer styles panel and the fill content panel
select the preset type to gradients
load gradients GRD file
The good thing about the replace and load means that you can add the GRD files into any folder and not rely on the Adobe's folder structure and especially useful if you want manual control over where the files go and how they are added into the tool and also if you have multiple versions of the application and wish to still keep them active and the presets active in them.
In many cases, you may wish to load a lot of Photoshop gradient files in one go and have 1000s of presets added in your panel. This is quite useful if you are happy to trawl through a large panel of lots of very small thumbnails.
One approach that seems to work well in some versions is to select a set of GRD files
drag them into the application but it is likely that an error will appear as the application says that it does not accept the format (weird as it is a valid format)
select a number of Photoshop gradient GRD files
right click and select open with the version of Photoshop you want and all the files will be fairly rapidly added to the panel (though it is not instant)
you will then see the set and you can then select from 1000s of great designs (especially if you go for the 32,000 gradients set available on this site).
You can also just go to the save command in the panel and then save them all to a single GRD file. You can join all the gradients into a single gradient GRD file. I would make certain that you make a backup of the file in case of corruption. A good location would be the CC libraries