Called Kindle support.
Made the rep use his own K3 to try.....he wasn't understanding my problem.
THEN he understood what I was trying to say.
Apparently, logging on the
www.mobileread.mobi site is NOT going to be an option for the K3 users 'at this time'.
Logging into
www.mobileread.com is do-able.
No idea if it will be in the future.
Disappointing.