I want to create custom membership registration module, Explain me

Before you start on that route, consider Dynamic Registration and Dynamid Forms from Data Springs.

Also, how do you want to customize the registration module? Perhaps it is something that already exists?

Thanks Joseph Craig ,

I want to create my own custom fields, For example FirstName, LastName, Email, State, Education Qualification(Dropdown List) and it will store on asp.net membership table, Here i assume email as Username and LastName as password. How I will create it.

Hi sir,
how to create custom membership provider in dotnetnuke.

Things like first and last name, email, and state are built into the user profile part of DotNetNuke. You can easily add custom fiields, including dropdown lists.

These tutorials might help:
How to Manage Profile Properties in User accounts (Creating a custom registration page)
DotNetNuke User Profile Features v5.4

MOdules like Dynamic Registration and Dynamic Login (both from datasprings.com) may be very helpful in doing this.