Choose Offers in the main left menu.
Click the New Offer button.
Define a Name for your offer. Select Affiliate network and you will also see the complete list of variables, that will be automatically passed to affiliate network. Setup postback URL in your affiliate network to receive conversions. If your Affiliate Network may pass you payouts, remove square brackets from the Postback URL. Replace CLICK_ID (and PAYOUT_USD if needed) with appropriate variables (depends on Affiliate Network, usually your Affiliate manager can help with this).
Read further: "Intro to Lander Setup"