Penetration Test and Port hole scan

I recently took on a new client that is a Credit Union.  The banking auditors from the Dept. of Banking and Consumers Finance are doing a site visit and asked when was the last time they had a Pen test and Port test done.  I have never done a Pen test and want to know how to go about doing this?  From some of the research i have done this seems to be a very detailed field and requires some in depth knowledge about hacking, vulnerabilities and security.

Is there some software I can buy to perform such tests?

Thanks,

Lee

Networx