Amazon does all the work for you. You will pay the cost of the book(the title's selling price) and the cost of shipping. You pay upfront and they deduct it when they send the copies out. this is more convenient than Goodreads, but more expensive. Remember that if you are an Create space author, you can order your books at cost plus shipping. so next time you place a bulk order consider adding a few extra to promote as a give away on Goodreads. this way you only pay for cost plus book rate shipping prices.
Don't forget to tell everyone on your social networks and other places!
Have some suggestions on unique ways to promote your new book? Let us know!