Lisa used the high-impact drill we bought for drilling holes in the concrete driveway during the trailer shelter assembly project to drill a hole in the concrete to which she attached one of the beams using this L bracket. This was where I had a weighty contribution to the project: I stood on the top beam to hold it in place while she drilled the hole and drove the concrete bolt into the hole.
The original beams (lighter colored because they were made with untreated wood) merely sit in their space held by their own weight, although the deck boards are nailed to them. Lisa hasn't decided whether to try to bolt them all into place.
It looks like we may still be one board short, because one of the boards we originally got that has been sitting there waiting to be used warped rather badly. So we may need another trip to Lowe's. On the other hand, there are other pieces of lumber we're considering getting as well, so once we have our plans together, Lisa will hitch up the trailer and we'll make another lumber expedition.