Prepping retaining wall for laying brick?

Approx. 2 1/2 years ago built a 12"H X 50'L retaining wall using 'split face' cinder block, I used rebar to support the retaining wall then filled with cement and leveled. I now want to install brick on top of the wall but after these few years not sure how to prep the surface? I would also appreciated comments/suggestions on the type of mortar I should use?



Thank you! Dave