These steps find their practical use “if your brother sins against you.” While there may be situations of other kinds of conflict where the model of private before public can well be followed, this procedure was given to address one kind of conflict: “if your brother sins against you.” This is the situation of a private offense. Our reaction should be just as described by the Lord. To be hurt, then hold that hurt in your heart over several years is never recommended in the Scriptures! To complain and gossip is not the right response. “If your brother sins against you,” you are obligated by virtue of discipleship, to follow the Lord’s method of conflict resolution. Go to him.
Step #1 is to “go and tell him his fault between you and him alone.” Necessarily implied in this is, the matter is private. You are taking a private matter up with the alleged offender privately. Based on this, at the first thought that I have been sinned against, I need to GO, not stay and sulk and go and tell others. The Lord said, “go and tell him his fault,” and do this privately at this point: “between you and him alone.”
The hope: “If he hears you, you have gained your brother.” If you approach the guilty party with right attitude and sufficient evidence, and this is combined with a receptive, humble spirit, “you have gained your brother.” In the case of sin proven, there would need to be repentance. (In some cases, since we are fallible, our perception of sin may not be reality. Once the misunderstanding is cleared, the matter is over.)
Step #2 is, “…if he will not hear, take with you one or two more, that, ‘by the mouth of two or three witnesses every word may be established’.” In modern lingo, you “kick it up a notch” now. This doesn’t mean you get angrier, campaign or gossip! The “notch” is defined by the Lord: “take with you one or two more, that, ‘by the mouth of two or three witnesses every word may be established’.” These witnesses are not “on your side,” and their function is not to “gang up” against the offender! You are not getting your friends to help you fight a battle. You are asking fellow disciples to listen objectively to the matter. “Witnesses called in at this level should have impeccable integrity and be people whom the accused will recognize as fair and impartial,” (Ken Chumbley, The Gospel of Matthew, p.#329).
Additional steps: http://www.bible.ca/ef/expository-matthew-18-15-17.htm