Membership and Roles help needed

I am new to asp.net. I will be working on a web application that will be using Membership and Roles. The application that i am working on is a B to B application. I want to customize the application such that all the companies who are registered will have accounts with the application for each company there will be a administrator for the company who will be responsible for creating accounts for the users and he will assign authorization to the users. As it is a cusomized application different companies (majour players) will have different business rules to be implemented. I also want a  super user account who will be resposible for creating the company account for the first time. Roles played by users will be different in different companies. So in asp.net if we want to create user ...