Select+ to create a new chat room (Figure 1):
Figure 1 Create
Search for the desired members to add to the chat room (Figure 2):
Figure 2 Add people
Select Create a Chat Room (Figure 3:
Figure 3 Create a Chat Room
Add a name and select the desired chat room settings (Figure 4):
Figure 4 Chat room settings
Select Create Chat Room (Figure 5):
Figure 5 Create Chat Room