Use the answer boxes on the Challenge page. You will only see this if you are the Team Captain, as only they can submit your answer. If you are not the Captain you will see a reminder of this. If your Captain is not going to be available to post the team submission for a particular round they can either delegate another member of the team as Captain, or give a deputy the Captain’s login username and password so they can submit instead. If you think you might need to do that there are things to be aware of. The erstwhile Captain cannot just take the Captaincy back, they need the new Captain to delegate it back to them. And if you share your account details then whoever knows them can post on the Forum as you.