When you first open Balsa, you will see a window divided into three which displays your mailboxes and messages. The local folders (on the left) are stored on your Psion LX, so you can create and view messages in these folders when you aren't connected.
When you connect to the internet, you can transfer (or "download") messages from your Remote mailbox to the local folders on your Psion LX.
When you open Balsa, the following local folders are displayed:
You can use local folders in the same way as you use folders in the File Manager.
You can create a new folder by tapping File/Mailboxes/New Mailbox.