Contracts are given out daily in three different types;
Easy Contract: Entry fee - $100 & Reward - $300
Hard Contract: Entry fee - $500 & Reward - $1000
Insane Contract: Entry fee - $1000 & Reward – 50 Crowns
You can check current Contracts either while in a lobby or on the Profile screen accessed from the Main menu. You can only choose one contract each day, and once you complete it you will see a time until new contracts are available. Simply complete contracts of your choice, on 30 different days. It is advised that you always choose the Insane contract as you will need the crowns for the "Fit for a King" and "Oooh...Shiny!" achievements.