Barry, on the CBS page, go to "League". Under League you will find "Trade Block", Click on it, then click "Edit Trade Block.
Check the player boxes you wish to put on your trade block. Click Submit.

Do remember, when trading (acquiring) for draft pick you will have to give a draft pick in return. It can be your final pick (#26). The only way this works at our draft site (Couch Managers) is if all teams have 26 picks in our draft.