At the end of the checkout phase, the customer is shown a receipt. At the bottom of the receipt there is a 'Done' button that takes you back to the starting page of the catalog (normally 'index.html'). However, it is possible to customise this button so it will take you to wherever you want it to.
To do this, go to 'Design | Design Options'. Tick 'Remove Custom Frames in Checkout' and enter the URL of the required destination page in the 'URL for Completed or Aborted Checkout' field.
To do this, go to 'Design | Design Options'. Tick 'Remove Custom Frames in Checkout' and enter the URL of the required destination page in the 'URL for Completed or Aborted Checkout' field.