Hi Maggie,
I started off with a top bar I built. I had built it and then got a cut out, so I made the rest of a frame to help tie the comb to. The bees I had in it were very gentle. As for the top I made the bars to fit the space front to back of hive, very little space, the I fixed a cover over the bars, kind of an arched deal that fit over the frames. Once you get your TBH done how are you going to extract your honey. And a TBH is heavy to move, if you have to. I have thought for years about building a long hive using Lanford frames, probably mediums for the ease of extracting. You would just get a frame or two out at a time inspect and take out another and replace it leaving a gap to work from.
I did love my TBH I had a window down one side with a cover over it. Could raise the cover and watch the bees do their thing for hours. Oh, I also put a wire mesh #8 hardwire in the bottom of the hive with a tray with oil at first, then I switched to water with a cheap dish washing liquid in it. It was closed where the bees couldn't get in it. Maybe this will help a little, I did go to Mr. Bush site and others on u tube.
Good luck to you and your bees,
Joe D