Hello,
It seems that many agencies want a reference, often from another agency.  But if they all want reference from another agency, how do I get started with my FIRST agency?

Check out P411, they will clear you and most girls take them.

Also, skip the agencies and try an independent. Many of them will take a newbie if you pass their background check. Getting started is tough but once a reputable girls sees you, white lists you and hopefully gives you a good referral you're set.

For this newbie, what's whitelist  mean, and how secure is it to be on it...?

It means that the provider is going on record here on TER that you are a legitimate hobbyist.  Other providers may or may not accept whitelisting as a reference.

thanks for your kind reply to my ignorance.  really appreciated.

yes, thanks for the advice!