Quick 'Step by Step' guide.

  1. Get chalk and mark the order of the bricks so that you put them back in the same places. You're only going to take off the broken layer of bricks.
  2. Lift off the loose bricks and remove 'most' of the mortar with a chisel and hammer but without breaking any bricks since you'll have a difficult time finding replacements that match.
  3. Lay them out on the floor nearby in the same pattern as you take them off the wall.
  4. Clear away any dust or loose debris and wet all surfaces that will be joined with mortar.
  5. Mix the mortar as per the 'ready mix' packed instructions but remember if you do this on the driveway it'll leave a mark and stain so use a thick plastic sheet / bucket / tray or similar.
  6. Evenly spread an amount over the wall top surface leaving a gap around the edge to match the layer below.
  7. Line up the first corner brick, position and tap gently to bed it in place. Use a spirit level or something long and flat to ensure you're creating an even and flat level surface. Place an amount of mortar on the side of the next brick matching the thickness of the layer below and making a curved pattern to allow the rainwater to drain off. Look at the other wall bricks and you'll see what it should look like.
  8. Repeat with the remaining bricks ensuring they are all tapped down and bedded in firmly.
  9. Lightly spray with fine mist of water and use a thin flat edge (finger) to smooth and even out the groove of mortar but without making a mess.
  10. To clean off excess mortar or marks you've made on neighbouring bricks use a 'tilers' sponge and 'dab' the mortar marks you'd like to remove, rinse out in water before repeating and you'll soon clean up any mess before it sets or stains. 
  11. If it's likely to rain cover with a loose plastic sheet that is weighted down to stop it blowing away.
  12. Mortar can take a few weeks to 'cure' and harden properly so don't be tempted to check if they've stuck for at least a month.