If you have a quote in the system, that is less than 30 days old, you can "flip" the quote to an order. This will create an copy of the quote as a new order with a new order number. Your quote will remain as a quote with the same quote number.
The steps are as follows:
Click the Manage Account menu on the header.

Select Quotes from the side menu and click the arrow to the right of the quote you wish to flip.

From the Quote Details page, click the "MORE" menu in the top right corner and then click the "Accept Quote" option.

There will be a small message in the bottom left indicating your quote has been submitted.

Once the order is created you will see it in the Orders section with the same PO as the original quote.