How do you make customer log on

Is customer log in the same as Joomla registration process?
Is it possible to add more fields?

not sure I follow,
Can you provide more info about what you're trying to do?

Thank you for replying back.

I'm a bit of newbie when it comes to database driven websites.
I am trying to make a registration form open to public to register and once registered they can make a booking.

What are the process in making a registration form to allow the public to open an account with us and make a booking.

Best place to start is to create a new Chronoforms form and use the registration plugin.
There are posts all over this forum regarding how to make that work.
You can add all the extra fields you want.

You'll need to either find a Joomla extension that will do what you want regarding "booking", or create your own. Go to extensions.joomla.org to search for extensions that might work.