It's all described in
Setting Up Locations, Designating Units and Building Schedulers. It's part of the calendar "Help" file.
While he's in there, make sure the list of rooms in the right column works for you. Obviously you don't want rooms checked off that your building doesn't have, but you do need all the rooms that you'll be scheduling. Or perhaps you need custom names. For example, in our building the multi-purpose room is also the baptismal font. So we have a "Multi-Purpose Rm/Font".
Keep in mind that you can easily add room, but removing them can create problems if events are already scheduled for them.
Have you searched the
Help Center? Try doing a Google search and adding "site:churchofjesuschrist.org/help" to the search criteria.
So we can better help you, please edit your
Profile to include your general location.