Ask a friend or family member to hold the shelf up against the wall. Back up and look at the shelf from a vantage point further away to ensure that the height and location are precise.
Place a level on top of the shelf. Adjust the shelf until the bubble in the level sits directly in the middle of the level's viewing field.
Mark the bracket locations on the mortar between the bricks with a black marker. Drilling through mortar is much easier than drilling through bricks. The number of brackets you need will vary depending on the size of your shelf.
Fit your drill with a diamond bit drill tip that coincides with the width of the concrete screws. Push the drill bit through a piece of tape. Pull the tape up the drill bit to the length of the screw. For example, if your concrete screws are 2 inches long, the tape should be 2 inches from the tip of the drill bit.
Put on protective eyewear. Drill holes into the marks you made on the wall. When the piece of tape on your drill bit lies flush with the wall, move to the next hole.
Push the screws into the holes in the shelf brackets. Insert each screw into its corresponding hole on the wall. Tighten each screw.
Place the shelf on top of the brackets.