The Contracts tab offers a tutorial, also accessible by choosing to create one and choosing the ICA Facility Freeform Yacht map, which teaches you the finer details of creating a contract. You are unable to create a contract that you yourself can't complete, but the steps to set a contract will force you to making one by clearing the three dockhands working on Deck 00 using explosives. However you kill your target, it will record it and others will have to do similarly to complete.