How does confession actually work?

Confession is very simple. Christ gave the apostles the authority to bind and loose sins, and this was always understood to be given to the apostles, not to everybody. In confession we are revealing our sins to God in the presence of a priest, who is the representative of God, and his job is to offer correction and absolution. If the person does not have repentance, he does not offer absolution.

For instance, if somebody says, I need to confess that I'm living with my girlfriend, the priest can't absolve that sin, because he's going right back into that environment. Confession always involves both the revelation of sin and the turning from sin. As St Nicodemus brilliantly says, anyone who goes to confession should go with the firm intention of turning away from whatever they confess.

So we must be thorough in examining our souls and laying bare what burdens our conscience. And keep in mind: it is Christ who removes the sins through the priest. The priest is not God. He has been given the authority from Christ, and Christ himself removes them.