Determine the size of your footer. As a general rule, footers are twice the width of the wall and equal in depth to its width. For example, a footer for a 6-inch-thick wall would be 12 inches wide by 6 inches deep, not accounting for the layer of crushed gravel and sand that usually is put beneath the footer. Usually this consists of 4 to 6 inches of gravel and 2 to 4 inches of sand.
Dig down with a shovel until you have a trench that is as wide and as deep as you need the footer for your brick wall to be. Measure this with a tape measure to determine the length, width and height of the footer. Transfer those measurements to wood material, which varies in size depending on your footer. The use of 2-by-12-inch boards is common, as is 2-by-6-inch boards or 2-by-8-inch boards. Cut the pieces to the appropriate length and width with a circular saw.
Attach the form boards to each other with the drill and screws, and lower the frame into the trench. Alternatively, you can put the pieces in the trench first and then screw them together. Keep the screws along the top section of the wood forms visible so you can easily remove them for disassembly after you pour the form.