1. Load Photoshop.
2. There are two ways to add Gradients in Photoshop, one by using Gradient Tool and other by using Gradient Command. First of all pick Gradient Tool so you will notice that top Property Panel would change. There you will get Gradient Picker , click on its Down Arrow and click on Add button:
3. Click on Load Gradient option and then selection your desire Gradient File in .GRD extension, which you just downloaded from Trendykit (Don’t forget to Unzip that file). So you will have a lot of gradients like:
4. If you want to use Gradient Command, then goto Layer >> Layer Styles >> Gradient Overlay, so you will see Gradient Picker there in the box, do the same thing as we did above so you may have a lot of Gradients too.