SQL Server Operating system error 5: "5(Access is denied.)"

SQL Server Operating system error 5: "5(Access is denied.)"

I am starting to learn school and I have a book that already gives a
database to work on. These below are in the directly but the porblem is
when I run the query, it it giving me this error: Msg 5120, Level 16,
State 101, Line 1 Unable to open the physical file "C:\Murach\SQL Server
2008\Databases\AP.mdf". Operating system error 5: "5(Access is denied.)".
CREATE DATABASE AP
ON PRIMARY (FILENAME = 'C:\Murach\SQL Server 2008\Databases\AP.mdf')
LOG ON (FILENAME = 'C:\Murach\SQL Server
2008\Databases\AP_log.ldf')
FOR ATTACH
GO
As in the book, the author says it should work but it is not working in my
case, I searched here but it is not exactly what my problem is, so I
posted this question.