We will be using this basic pink background for this tutorial:
Go to Adjust > Add/Remove Noise > Add Noise
Select Monochrome & Gaussian. The amount of noise depends on your personal preference. But for the sake of the tutorial I will be using 40% noise.
You can change the amount if you'd like (usually for really nice backgrounds I'd use the 10%). Now press okay and you're all done! You can try applying this to images and using as effects if it works for you. And you end up with something like this:
