How to extract domain users credentials

I need to develop an web application using ASP.Net and C# where I need to know the domain user's login and log out time. Let me explain the situation briefly. There are a domain server (DNS Server), a web server and a database server along with 100 client PCs in my organization. Each user in these 100 PCs need to give domain user name and password while logging in. The web server and database server are also in the same domain. Now when any user access the url of my web application the web app should know the details of that user like his domain name, log in time in the domain or log out time etc. Will you please give me some light on this? I need to know the technology and how should I proceed?
...