For the newbies - you can ‘bid’ on a player to join your roster, but you must drop a player from your team in order to do so.
So for example, one of your players has suffered a season ending injury, you should go and drop him and replace him with someone from the available free agent pool (aka the waiver wire). Bid priority goes in reverse ladder order of the current standings, so Scotty has the #1 bid for this week.
It’s tough any week, let alone the first week. The vagaries of your RB being stopped an inch from the line, and then your opponents WR getting the touchdown on the next play……