All your invoices are available in your Accounts area.
Click on your name top right and then Manage your account
Once in the Accounts area, under the Billing Tab you will find your current payment method and under that you should find your invoices.
Note: if you have only just upgraded to Fabrik, your new invoice will not appear until your Trial ends so check back another time.
Click on the invoice to view it, from there you can print it directly to a printer or if you if want to save it as PDF you can use your computers in built Save as PDF option when printing.