Q: What are textures?
A: Textures are images that blend with your background image that give it more complexity and often makes your image look better.
How to use textures
Textures are quite easy to use. First, take an image that will become your background image. Now you can get a texture from many sites on the internet. It's really simple: you just type textures into any search engine.
Once you find a suitable texture that will fit on your image, you copy the image and paste it. When you paste it, the texture looks like it covers the whole image. However, this is not what you want it to look like. For starters, you can change the opacity of the texture layer. This however, is well short of what Photoshop can do.

For more ambitious people, there's also another option where you can change the blending options of the image. First of all, click the small “f” at the bottom of the layers window.

Next, you will see a window with many different blending modes. Experiment with the different types and opacity. Below you can see I have used the “screen” blend mode with 75% opacity to create this effect.

I have created a nice effect using the texture.
Happy texture using and await my next tutorial - patterns!