Making a Grid

1. Create a new 165 x 165 pixel. Now fill the document with any color you want.Show channels and create a new channel. Press D then X, then use the rectangular marquee tool and a selection 20x20 pixels, hold down shift to make perfect square. Then fill it with white. Then press the down arrow once and the right arrow once, press delete, then press the up arrow once and the left arrow once. Leave the selection, then go Edit > Define Pattern..Name it whatever you want (I used 'grid'), then deselect.

2. Now create a new channel. Then select the paintbucket tool and in the top toolbar, change the fill type from Foreground to Pattern.

Now click on the your pattern,

and then click the paintbucket anywhere on the canvas.

3. Now load the selection from the 'alpha' layer and then show layers. Create a new layer and fill the selection with a color of your choice (preferibly one that contrasts the background color your chose). There you have it, easy way to make a grid.