Fill in the global rating and the morale to estimate the salary a player wants. Indicate if the contract is meant for a new player (transfer market).
The result is the minimum the player will ask, usually you'll have to raise the calculated values a bit to have the player agree with the offer.
There are 4 options displayed in the result: only salary, only win-bonus (if possible), only sign-bonus, and car + house + salary. Of course you can compose your own preferred distribution.
Salary: paid each official match (league/cup).
Win-bonus: only paid if you win an official match and if the player is part of the selection (11+5 players).
Sign-bonus: one time payment depending on the duration of the contract.
House + Car: cost € 900 each per month, so both is € 1800.