Make sure you have breakout rooms turned on. From clu.zoom.us go to "Settings" the breakout room switch is half way down the page.
Once your meeting is started, click on "Breakout Rooms" from the bottom menu. A dialogue box opens allowing you to select the number of rooms.
Select manual assignment and a dialogue appears with the number of rooms selected.
When you click on the "Assign" button the participant's names will come up. Select the participants for the different breakout rooms. Each participant will receive a message inviting them to their breakout room.
The host should see a "Breakout Rooms" In Progress dialogue. From here you can close the rooms when the breakouts are done