First, your product needs to be set as a "Normal Product". Daily Deals do not work with "Make Offer" or with "Auction" products. When you are looking at your products list, simply find the product you want to place a Daily Deal on.
Click the action tab to the right, then in the drop-down choose "Add To Deal". When the screen pops up simply choose the date you want it to start and the deal price. The time will automatically be set and that is not editable at this time. It is system set and the product will go live on the Daily Deals Page at that time.
Once submitted, this will display on our Daily Deals page for 7 days, then automatically come back down. If not sold, be sure to go back and change the product if you wish to allow for offers again or to turn it into an auction.