When you create your new Overflow account, an organization named "<firstname> Organization" is created for you.
To create a second organization in Overflow, go to Overflow Cloud and sign in to your account. You'll find the Organization menu at the top left of the Dashboard. Under the menu, you can find the option to add a new organization.
Click "+ Add Organization". You'll be taken through the steps of purchasing a new subscription. Depending on your team's size and needs, you can choose the number of seats and billing cycle (monthly or yearly).