Once you have logged into your account you will want to navigate to My Invoices.

 

 

At My Invoices you will see the following screen:

 

 

For open invoices. You will click on Pay:

 

 

In the middle right you will see a Download PDF which you will click on to obtain a copy of your invoices.

 

For Closed invoices:

Click the View button

 

 

And in the top right you will see a Download PDF button: