The TRANSFER MARKET is where you will find all players that other clubs have listed as available. The list on the left shows all of the available players and you can sort by any of the headers, which are:
BP: Best position
MV: Market value
Before you make a bid you can find out more information on a player by tapping SCOUT. One of the pieces of information you can discover is whether the player has a RELEASE CLAUSE in their contract, meaning, if you match this value, that you can bypass transfer negotiations and deal directly with the player.
Once you have decided to make a bid you can tap the BUY button to make a bid. The selling club will then contact you with their decision via your INBOX.