This was the first anchor. Lisa dug holes and I mixed concrete. We poured the concrete into the hole and embedded threaded steel in the concrete, then bolted that to the Z-brackets that attach to the base rail.
In places where there was no place to dig a hole (generally where the rail was too far from the edge of the existing concrete pad on account of the pad isn't quite square), Lisa used a concrete bit to drill anchor points.
Lisa wrestled with her regular drill for a while before concluding that we needed the right tool for the job, and the regular drill wasn't cutting it (literally). We went to Lowe's and bought a hammer drill (the yellow drill in this picture). This worked very well; it drills holes in the concrete very quickly.
The existing pad is not only not square, but it's also not quite level either, and thus there is a place where it's attached to the concrete but with a gap under it.
In some places, there is both a concrete post hole and a drilled hole. In this case, Lisa dug the post hole slightly undercutting the pad, so that the new concrete goes under the existing concrete and means that the entire pad is aiding in the anchorage.
Lisa was very concerned that this structure not blow over in the wind storms we get here. With both concrete bolts drilled into the pad and additional concrete post holes holding it down, we reckon that nothing short of a tornado is going to budge this thing.