How to implement Login functionality using ASP.NET WebForms and existing SQL Server database?

I have a SQL Server database that I made using Visual Studio's LocalDB. It has 5 tables, one for the Employee information and credentials, one for the location codes of the offices of the company and others for the meetings he attended and the tasks assigned to him.

I am mainly looking to implement Login functionality on my WebApp. How do I access the SQL database and implement Login? I have currently connected the database and used ADO.NET Entity Model to access the database. I am looking to avoid stored procedures. It would be best if the someone explained how to do this with ADO.NET Entity Model and the Login control.