Confess and Repent
Outside the church, the word "confess" is mostly used to describe criminals who have told someone what they have done. In the church we have an additional meaning for the word. When we have done something wrong we confess to God what we have done.
As part of that confession we understand that we, as criminals in the eyes of God, have broken the law and are guilty. Therefore you can see how the way we use the word in church is really the same as we use it outside the church.
Our understanding of the word is a bit deeper though. We see the wrong things we've done to people are also wrong things done to God. After all, it is his standard for our behavior that we've broken, not a standard set by man.
Part of a confession also involves the recognition that someone was wronged and usually that you are disappointed in yourself. This often involves sadness.
Repentance is the next step after confession. Having recognized that wrong was done, repentance is the rejection of that wrong act as a part of one's future, a commitment to never do it again and to live according to the standard. Repentance is often described as turning one's back on what has been done. This does not mean a denial that it ever happened. It does have the additional imagery of leaving some junk behind and moving away from it.