Every activity that requires you to make any kind of contract offer to a player goes through the same screen format.
You get a drop down menu with the contract lengths that can be offered to the player (as defined by your league's rules), and a place to enter the total contract amount and total bonus amount. When you're done, hit the Submit button.
League Pulse processes your offer and shows it to you so you can make sure everything was input correctly. If it looks good, click Yes to submit the offer to the league. If you need to go back and re-enter the values, click No.
Entering Contract Amounts It follows the same format as Madden, which should make it fairly intuitive.