user level authentication

Hi,

(The way I learned to do this is with a field Admin in the database enum('n','y'), then create 2 radio buttons NO and YES ( Dream Weavers Wizard) set to NO as default. This is to make the choice between normal visitor NO default (do nothing) or Admin (YES) )

I can understand all tutorials about how to apply the authentication, but what is missing is the part before.

Of course on a real world login page you don't type Visitors in the username field (like in the WA tutorial), in my case you type the email address that is always different for every visitor.

What steps do I have to take so that a normal user is recognized as a Visitor with that email address and password. The same question about the Administrator.

I understand all steps concerning User Level Authentication and page directing, but I miss the couple of steps before in the database. Do I have to make a field with the visitors/administrators login code stored in it? That part I don't get!

Can you please explain this in detail to me?! Thanks in advance!