how to use row number function in sql server

1-- Uses AdventureWorks  
2  
3SELECT ROW_NUMBER() OVER(ORDER BY SUM(SalesAmountQuota) DESC) 
4    AS RowNumber,  
5    FirstName, LastName,   
6    CONVERT(varchar(13), SUM(SalesAmountQuota),1) AS SalesQuota   
7FROM dbo.DimEmployee AS e  
8INNER JOIN dbo.FactSalesQuota AS sq  
9    ON e.EmployeeKey = sq.EmployeeKey  
10WHERE e.SalesPersonFlag = 1  
11GROUP BY LastName, FirstName;  
12

1USE AdventureWorks2012;  
2GO  
3WITH OrderedOrders AS  
4(  
5    SELECT SalesOrderID, OrderDate,  
6    ROW_NUMBER() OVER (ORDER BY OrderDate) AS RowNumber  
7    FROM Sales.SalesOrderHeader   
8)   
9SELECT SalesOrderID, OrderDate, RowNumber    
10FROM OrderedOrders   
11WHERE RowNumber BETWEEN 50 AND 60;  
12