Hi,
I installed zenphoto for my domain. Everthing looks wonderful but the login form. I managed to display the register form, but I haven't found out how to make login form on the site.
I need an urgent help.

What login form?

The admin login form is (assuming you have mod_rewrite) www.yoursite.com/zenphoto/admin

If your site requires a password to access it then when a visitor views the site and is not logged in he will receive a login form. If the site is public, then what would the login form be for?

There is a plugin which will provide a login field on your pages (wherever you place the function call) if that is all you wish.