A stake admin will have to do it. Gear Icon > Locations & Rooms > select building > click "edit" in the middle column.
Click "Add' next to "Additional rooms & equipment" in the right column.
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.