Add a cash/cheque payment

From your 'My Hub' page (please see below)

On the left hand side of your account, you will see the side menu where you can select 'Financials'.

Click the 'Receipts' tab from the 4 options at the top of your page. 

You can then create a receipt by hitting the 'Receipts' button at the top of the page.

Here you will be able to add all the details of the purchase including whether it was a 'Cash' or 'Cheque' payment.