In the station details screen, you see the list of stations that have already been mapped to your routing. This means any work centers that you've mapped to operations in the routing will show up here. If you want to add a new station that doesn't yet exist in the database, you can type in a new station name.
If you want to bring a station that does exist in the database from the plant editor, you can click on existing and you can add a select and add a station here. You can set the operator counts for each station. I have two in my frame and add-ons station because I had to find two different operator IDs for activities in the operations that are mapped to the frame and to the add-ons work centers.
You can also choose to exclude a station from the scenario and you can also define a setup time if there is a specific set up time for a particular station you can add that as a block of time. That time won't get rebalanced or moved when other tasks are moved but it's a way to specify that there is this set-up time that needs to be accounted for.
When you're done with these inputs you can click finish and your scenario will be created.