Then your Google-fu skills need a lot of inprovement.
A
very quick search[
^] using "Datacontext in Linq in c#"
copied and pasted from your question as the serach term found 288,000 hits, including a walkthrough as the second link:
Walkthrough: Simple Object Model and Query (C#) (LINQ to SQL)[
^] - which covers just that.
Try to learn to do at least elementary research...