Step 3: Drawind the mask pattern
Follow the picture and use the permanent marker to draw the pattern onto the board. The objective is to etch away a line in the middle to separate the two pads/areas. You want this line to be thin so that an SMD component can actually touch both pads. While you could fill the rest of the board it is advisable to leave some empty areas around the holes. This will serve as thermal isolates and will make your soldering job easier.
Let the ink dry for 15 to 30 minutes.