First of all, there are four steps: Layout, Constrain, Solve and Results
This page is the Layout step. Here you can create the seat layout you want.
Lets go through the steps:
1. Give your project a name using the Change Name button
2. Select a Grid Size that is large enough for your needs, which you confirm using the Set Grid button.
3. Now its time to add tables to your layout. Select a table size in the drop down, and click Add Rect or Add Round, which creates a Rectangular/Round table in the middle.
4. Drag the table to your destired location. You can join tables by just putting them next to each other. The seats (green circles with numbers) that are obscured by the join are automatically removed.
5. Right Click a table for more options: Resize, Rotate 90deg, Label, and Delete
6. Once you have the destired layout, you can toggle/deactivate seats that are not supposed to be used by right clicking the seat, which turns gray.
7. To see which seats are considered Neighbors (next to each other for later rules), just hold Left Click on the seat. The seat itself turns blue, and its neigbors turn yellow. This is important for the constraints.
8. You can change the Neighbor Radius at the top.
9. To save a seating layout, click Export Seating, which can then later be imported using Import Seating. Clear removes everything.
10. Once you are happy, click on Continue (constraints) for the next step.