Create User Roles In Asp.net Web Application project

I need guidance from all of you experts for a simple task. i'm working on my final year project which is a web based application. In this application i have to create several users which will do different taks for example accountant will manage fee and admin will manage teacher and student accounts and so on. i'm working hard on this and I've learned simple authentication. I'm able to authorize users based on their user names and allow them to access specific pages or specific folder having multiple pages. I'm doing this by using form authentication. but now as i want to create user role and assign different roles to different users so that I don't have to add each and every user name in web config file. please suggest me the easiest way to do this. is there any book, or article or youtube video from where i can learn it ? I've searched stack overflow and msdn but i'm unable to understand. I'm waiting for your suggestions, thanks in advance. I'm nor working in MVC. I'm using .net 4.5, visual studio 2012 and sql server 2014