Whre to get the administration guide of check_mk?

My company currently using check_mk v1.2. This monitoring software was installed on a suse 11 sp3 server. However, my application team members always have some "doubts" especially on the threshold we set plus some others. This is because they always facing the CRIT state on their applications that under monitoring. We as the administrator for the this software need  to have a further understanding on how to "play around" with this threshold and other settings.

btw, where can we get the administration guide of this check_mk?

Thanks in advance.