To play in a free slot tournament on Casino Guru, you need to be logged in to your Casino Guru account. If you do not have an account yet, you need to sign up first. You cannot create multiple accounts to increase your chances of winning. Also, you need to be at least 18 years old (or the legal gambling age in your country) to be allowed to play.
Anyone who meets these conditions is eligible to compete against other players completely for free. No deposit is needed nor possible. There is no way to increase your chances of winning by spending your own money.