In order to become a skilled Christian counselor, one must understand how anger works in the human mind, as well as how to properly address it and deal with it in a Scriptural context. Anger is very much a constant in the Bible, from the wrathful God of the Old Testament to the suffering of the New. While God's own wrath is justified and permissible, human wrath is always soundly criticized (Collins, p. 159). At the same time, several things are shown about human anger - first, it is normal and not a sin in and of itself. This is shown in Ephesians 4:26: "Don't sin by letting anger gain control of you. Don't let the sun go down while you are still angry." Another thing to keep in mind is that human anger often comes about from faulty perception; we may be angry about something that we don't fully understand because of our limited perspective (Collins, p. 160). Furthermore, while anger is not a sin, it can lead to sinful behavior very easily. Making these points apparent to those you counsel will go a long way toward establishing how the Bible feels about human anger. In order to address anger, it is important to face the source of the anger as well, so that the individual reasons for becoming angry are understood and recognized. Maybe the person feels an injustice towards them, or it has a biological source. Turning the energy from that anger into more constructive pursuits is always wise to suggest (Collins, p. 168). One cannot simply get over what they are angry about, so the sources must be confronted and dealt with.
References
Collins GR, 2007, Christian Counseling: A Comprehensive Guide (3rd ed.), Thomas Nelson.