To add, edit or delete an account go to the Accounting -> Accounts tab. If you select an existing account you can select Edit Account or Delete Account from the option menu on the top right hand side:

Note that accounts cannot be deleted with any transactions or any subaccounts present.

To add a new account select the option menu near the top left hand side of the screen then click on 'New Account'

In the add/edit account popup window be sure to set the Account Type as well as typing in the Name and Number:

If you would like a new account to be a subaccount of an existing account check the Is a Subaccount button and a dropdown to select the parent account will appear:

If the account type does not match the parent account type you will be given this warning upon hitting Submit:

You can double check the parent’s account type by closing the window, selecting the parent account and clicking edit account. If you successfully add the subaccount it will appear under the parent account:

You can also choose to create an account for a specific company. To do that click All Companies in the the Link Account To section and select the appropriate company. This account will then only show in that company's set of books.