Hi Charlene, we just did this last year actually. We actually built a patio on a slope so we had to build a retaining wall first. We DIY'd the whole thing. I have ALL details in these posts starting it from scratch with all the math so you can build one yourself with stone!! If the plans and diagrams from the 1st post is too much.....go to the second post to see all the building pics. Hope this helps:
-describes diagrams and sketches needed to build a retaining wall along with planning the wall and cement pad.
-laid out how to plan and diagram a retaining wall.
-math calculations to figure out how much stone and block to order
-how far we dug down and the cross section diagrams of what is going on under the ground
-What we did to build the retaining wall.
-what materials were needed.
-the actual building pictures