You can process billing for select users or all. Go to Manage > Users > Billing Tab. Billing sends an email to all users selected. The email will include their flight history, payments, and charges. If you accept credit cards a link will be included for them to pay online.
To see the sent billing emails history log tap on Last sent (date) in the upper right corner.
To send a custom message along with all billing emails go to Manage > General Settings > Billing message (near the bottom) > Save Settings.
Automate billing by going to Manage > Users > Automation tab > Billing.
For the user’s view, they can see their account history by clicking their name menu top right > My Account. If you accept online payments, they can make a payment there.