C# linq to sql

Question

In a C# 2010 desktop application, I need to write a linq to sql statement that
connects to a sql server 2008 R2 database. I need to be able to use a group by
for 4 specific columns so that I can the count to be correct. I have
been trying to get the group by to work, with no success so far. Thus can you
show me some code on how to accomplish this goal?