Bays are the area for each section for the beams and blocks setup.

First of all, you have to define the bay area from the plan drawing, in this case, it will look like this.

Create Bay

When creating you select  and you will get 4 options, 

If the model is as simple as mine you can select Internal points of course the plans usually are not that simple then it could be a good idea to draw the areas as a polyline to make your work easier.

When selected the first bay you will get this pop-up window.

There you can define the name of the bay, write a small description, and also define in which building and floor this construction is. Press ok and you have defined the first Bay area. 

Edit Bay

If you need to Edit bay you can select  and select the bay that you need to edit. You will get the following pop up window where you have the options to make your adjustments.

Save Bay

To be able to draw your beams and blocks you have to save the bays.

First, you press  and then you can select the bays you would like to save.

Edit Layout

Edit layout is when you have added beams and/or blocks to the bay, then you have the option to make adjustments.

First you will be prompted with following:

If you select continue at this stage you will just opt out of the command.

Start with beam gives you the option to start with beam instead of the block is resting on the wall.

If you select Block orientation you have the option to adjust the blocks, and you will get the following options:

Next toggle from one space to another. Then you have the option to insert a cut block or remove the selected row of blocks.

Toggle orientation determines if you want the blocks to be rotated 0° or 90° to the beams.

Mirror bays

If you have a symmetrical building as I have, you can mirror your bays to the other side, and in that process, they will get their own names.
Just press  and select the bays that you would like to mirror and then select the plane you would like to mirror with.
One thing that I would like to point out is that if you have drawn beams and blocks to the bays, the beams and blocks will also be mirror along with the bays. That could be helpful in the design process.

By pressing ok you will get your mirrored bays, with or without beams and blocks depending on where in the design process you decide to mirror.

Remember to save the new bays.