Where is Chess960?!

Chess960 is one of the main options in Daily/Correspondence. If you are looking for it Live you need to be on v3 or the app.

I am on PC and have a new site version enabled, but cannot find an option to start LIVE 960 game.

 Play>Live Chess>New game.  To the left on the same line with the orange play button; see that little chessboard?  Click on it and a drop down menu is revealed with 960 as one of your choices.

Ah O.K. I can see it now. Thank you for help.

You're very welcome.  I didn't actually know for sure where it was so I just clicked around to find it and got lucky.  I generally pretty much refuse to spend any effort figuring out where stuff is on V3 because things keep changing.