Before your auction can go live, you'll need to set certain preferences on your listing. You can choose an opening bid, a reserve and the duration of your auction.
The Opening Bid is the minimum amount a prospective buyer can bid in your auction. This number should be low enough to encourage early bids, but high enough that it gives interested buyers an idea of your reserve.
The Reserve price should reflect the minimum amount that you're willing to accept for your website, domain or app. Note that auctions get even more buyer interest once bidding is past reserve, but that once the reserve is met, the auction will be won by the user who places the highest bid. Be sure to set a reserve for which you'll be happy to sell your property. The reserve is kept confidential until it is met.
Your auction duration depends on your calendar, your timeline for selling, and on the type of property you're listing. If your website or app generates a lot of revenue and traffic, it will take interested buyers some time to conduct due diligence. If your website or app has minimal traffic/downloads and revenue, it won't be as time consuming for buyers to place an informed bid, and you should set a shorter duration.