Navigate to "Recruitment" and click on the "Contracts" tile.

You can sort the "Expires" column to see players whose contracts expire soonest at the top.

Right-click on a player and select "Discuss New Contract With Agent". This is not strictly required, as you can also go directly to "Contract" -> "Enter Contract Negotiations", but by talking to an agent first, you will receive useful information about the player's expectations.

On the next screen, you will be presented with response options to show the level of your interest in an extension of this player's contract. You can experiment with different responses to see how it affects expectations, but usually, choosing "Slightly Interested" or "Interested" is good enough.

In the next step, the agent will present you with the player's demands. You can agree or contest them. Sometimes it is worth contesting the salary. Depending on different conditions (for example, the type of agent and his relationship with you), the salary demands can be decreased.

After finishing the discussion with the agent, end the chat, and once again right-click on the player, then choose "Contract" -> "Enter Contract Negotiations".

Finalise the promises.

Finalise the deal and exit the talks.