Lay out the first course of blocks (4) in the desired location, interlocking them to create a circle.
Repeat this for the next two courses of blocks while staggering the joints between them.
Place the cap pieces on top of the third course of wall block, keeping the inside flush, this creates the intended overhang on the outside edge. (The cap pieces will be revisited after next step)
Empty the sand into the opening of the fire pit and create an even covering. Next, insert the steel ring on top of the sand, pressing down until the top of the ring is even with the top of the inside edge of the caps.
To finish the capping process you may need to shim the cap block to create a completely level surface. Once the caps are shimmed and even, apply a bead of any masonry adhesive in between the caps blocks and wall blocks to secure them in place.