You need to create an Users table which contains some fields, like UserID, UserName, LastName, FirstName, EmailAddress, and so on. And then you can create two files. One is for a registration form and the other for its process. If you need more details or some samples, you can read the book "Beginning ASP Databases" by John Kauffman from Wrox.
And/or for a "quick and dirty" generic ASP open source solution to putting databases on the Web (often works well for the admin area of a Web site which doesn't need to look too unique) that just requires setting up a configuration page for each table or query and uploading the database to the Web as long as there is an autonumber field in each table (and you'll probably also separately want to create login capabilities), perhaps try something like this:
GenericDB by Eli Robillard http://www.genericdb.com and then click on the Tips link to see an example