This following example Query will clear how to filter records using where clause and group by from a set of records.
Many of us are facing problem with grouping elements this example provides best practices for one who wants to know group different types of data.
var result = from queryResult in db.Orders.AsEnumerable() where queryResult.ShipCountry == "UK"
group queryResult by queryResult.ShipCity into rowGroup
OrdersCount= rowGroup.Count() };