Registration system

I embedded a form in a website with signin required. The signin screen shows as expected but there is no option for a new user to sign up.

The application does not have to be very secure but I do need to know if they are a returning user or a new user. Should I build a form to gather the persons email so I can direct them to one page if they are a new user and a different page if they are an existing user?

If I ask for an email then I should also have a text field called a User ID. Both the email and the User ID would be required to see that users existing information.

If I have done that then I have a login system that is not very secure.

What is the best way to have users register for a zoho application? We anticipate hundreds of users maybe even more.

Herb Wexler