ausearch is part of the tools that come with auditd - in the 2.6 kernels. You just enter the commands at the prompt.
The configuration file is: /etc/audit.rules
Manage the rules with: auditctl
Get reports with: aureport
ausearch will query the audit logs.
If these packages don't seem to be installed, yum install audit
If you are having a specific problem or have a particular need, then please tell us.