You can use these screen to pickup free agents as well as drop players from your team. If the commissioner has indicated in the league rules that pickups and drops require commissioner approval, then any add and drops will be submitted to the commissioner and not executed unless the commissioner approves the add/drop. Also, the commissioner can specify an add/drop starting deadline and ending deadline, and you will be locked out from submitting add/drops outside of that deadline. As an example, if the commish enters a starting deadline of Tuesday, 5:00pm EST, and a ending deadline of Thursday, 11:00pm EST, then each week you can submit a free agent pickup request from Tuesday at 5:00pm EST until Thursday at 11:00pm EST. Outside of that deadline, you will be locked out from submitting free agent pickups. If the commish does not have to approve the pickup request, the free agent is put on the team as soon as the request is submitted. If the commish must approve the pickup request, then any time after the deadline, the commish reviews all the pickup requests and either approves or disapproves each one. This will then allow your league to use whatever league rules your league has to determine who gets a free agent if more than one owner wants him. For example, if the commish checks all the requests and sees that two owners want the same player, and your league rules say to give the free agent to the team with the worst record, the commish can then approve the pickup request for the team with the worst record and disapprove the other. When you select a free agent to pickup, you should also select a player to drop. If the request is approved, the commish should approve both the pickup and the drop, and then the free agent is put on your team and the selected player to drop is taken off your team. Note that it is not possible to enter pickups or drops from Sunday 1:00pm EST to Tuesday, 7:00am EST.
You can enter a note to the commissioner when submitting the add/drop request. This is useful if you want to submit multiple requests and want to let the commissioner know the order of priority of the requests. For example, say your league rules award free agents to the team with the worst record if two or more teams want the same player. So, you can submit a request with the note that this request is your first choice. If you think that the player you want may be requested by other owners and you don't have the worst reecord, you should submit another request for a different free agent with the note that if you don't get the first request, then process this second request.
In most cases, if you want more than one free agent, you should submit multiple requests. For example, if you want two free agents (Jones and Freeman) and want to drop Lee and Smith, you should submit two requests: one request to pickup Jones and drop Lee, another request to pickup Freeman and drop Smith. This way, if other owners want the same players and your league rules are such that you wind up only able to get one of the players, the commish can decline one of your requests and approve the other. If you had only submitted one request for both free agents, then the commish would have to decline the request and you would have to submit another request for the one free agent you are allowed to pickup.
The free agent list will include all the free agents by default. To limit the list to a certain position, choose a position via the "show only" drop-down box.