I am new to graphic design and photoshop. I found this app called Gear Rise by Nanovation on the App Store and was wondering if anyone knew how to create the frosted-like gradient in the background? I don't really know how that designer got those different colors in there and how it has a frosted look on top, it looks very clean and sleek and I would like to know how to achieve that look!
Terminology comes as you learn this stuff.
What you are seeing is a gradient blend. If you have access to Adobe Illustrator, I would suggest looking into learning the Gradient Mesh Tool
This allows you to make complex multi-colored gradients that can follow shape of the artwork.
As always I would recommend you look for some image reference to build a swatches for the colors your would like.
Here's a decent tutorial to get you started.