1.Unzip DHC2.zip into the Aircraft folder of your FS9 directory.
2.Unzip Gauges.zip into the Gauges folder of your FS9 directory.
3.Unzip FSSound.zip into the Modules folder of your FS9 Directory.
4.Add the below text

[OLDMODULES]
FSsound.dll=1

to your FS9.cfg file. The fs9.cfg file is located in:

Windows 2000 and Windows XP: C:\Documents and Settings\username\Application Data\Microsoft\FS9.

Windows 9x and Windows ME: \WINDOWS\Application Data\Microsoft\FS9

Use notepad to open the FS9.cfg and simply copy and paste the text at the end of the file