Check out example codes for "c# authorize attribute". It will help you in understanding the concepts better.

Code Example 1

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(
            Configuration.GetConnectionString("DefaultConnection")));
    services.AddDefaultIdentity<IdentityUser>()
        .AddRoles<IdentityRole>()
        .AddEntityFrameworkStores<ApplicationDbContext>();

    services.AddControllersWithViews();
    services.AddRazorPages();
}

Learn ReactJs, React Native from akashmittal.com