You will cash a cashier's check much like any other check you receive: by going to your personal bank, where you might have a checking or savings account, and cashing it there. The process is similar to endorsing a regular check, though a bank will probably ask to see your identification for this particular form of payment. The check will be deposited into your account, and will typically clear the issuing bank within two to seven days, which is when the money is "officially" yours.
At one time, cashier's checks were viewed as very secure forms as payment that were almost as good as cash. This is because the check is issued by a bank on its own holdings, meaning that the money is virtually guaranteed, barring closure of the bank between the time the check is issued and the time it is cashed. This method of payment was often used between two parties when one will not accept a personal check from the other, for fear that the check will not clear. Fraudulent cashier's checks, however, have made the process of trying to cash a cashier's check more difficult.
Though theoretically you should be able to cash a cashier's check at any bank, you will likely need to have an account at that bank for them to cash the check. This is because the check still needs to clear, and if you do not have an account at the bank, and the check turns out to be fraudulent, the bank has less recourse. Typically, when you cash this type of check, the funds will be deposited into your checking account; then, if the check does not clear, you will be responsible for it. This is why it is important to verify the authenticity of any cashier's check you receive by placing a phone call to the issuing bank, which will be able to tell you in a few minutes if the check is valid.
Otherwise, cashing a cashier's check is a simple process as long as you bring your identification, and the check is made out to you. Endorse the check properly as well by signing your name the way it appears on the check. You may choose to wait until the check clears to use the funds, but in most cases with verified checks, it is safe to use the funds as soon as they are given to you.