how do you make like a grid in the bg? I've seen it in a few sigs, like a pattern of dots in a grid formation. Can anyone help me?
Texture, go look in that feature and just mess around you should find a variety of textures you can choose from.
Make a new document, around 3x3 pixels (zoom in as far as you can, ctrl + +). Get the pencil tool, set it to 1 pixel and make a dot right in the centre of the grid. Go to edit>define pattern>ok. Then open up the sig/wall and go to edit>fill>pattern and it should be there. You can experiment with the type of pattern by making the canvas bigger and making different patterns.