From the software, click on the blue “File” tab in the top left corner and choose “New Account”.
A wizard will pop up, defaulting to “Create an Account…”
Click “Next”, assign a name to the account and then choose your Accounting Period ('Months' is the default).
Each account in Treasury Software will be connected to a different bank account. Continue through the wizard, and then the software will flip into that new account so you may continue with the setup.