To create a pool:
Navigate to the Play tab (second from the left).
Click the Manage button on the large ticket.
Under "More ways to play," click where it says "Pool Play->."
Click the button sat says "New +."
From there you can click on "Create Pool" and designate a name for your pool and how many of your tickets you want to allocate.
You can make the group private if you want to control who joins your group or public if you want anyone to be able to join using the Pool's invite code.
Confirm your settings by clicking the "Create" button.