Multisite configuration

[smiling]

I have a main website of example.com, and I want to add a second (and more) domain named example2.com, with a home directory of example.com/example2/
example2.com is a "parked" domain name, ie it is initially directed to the public root directory of example.com, the main account.

I am told I need.htaccess coding that will

1. set the public root directory of example2.com to example.com/example2/

2. retain the visible url of example2.com *after* internal redirection to example2's public root directory

So the user types example2.com, is taken to the public root directory of example2.com (through.htaccess programming), sees example2.com in the URL field of the browser, but in fact has been taken "underneath" to example.com/example2.

Can anyone show me how this is done, or point me to some documentation?

Thanks!