在Asp.Net Mvc 6中创建管理员超级用户

I am trying to code for creating the default admin super user from the Startup.cs in Asp.Net Mvc 6, I can add just the all the user roles, but I cannot automatically assign the admin user into the table of AspNetUsers. Can some experts help me to correct the problem as my embedded code below:I am trying to code for creating the default ad