Whit's Menu Error

Hey again guys, use may remember me from December 2010, when i coded a menu in Whit's Combined Source, i've just came back to coding and i have an annoying error.. i've added several hacks onto my menu but now when i go to compile/build i get one error..

This error may seem like im retarded, but atm im dumb founded trying to get back to what i DID best-

Error:
1>------ Build started: Project: Whits Base, Configuration: Release Win32 ------
1> Base.cpp
1>c:\users\QQiswhyihack\desktop\whit's base\cabase\Files.h(15): fatal error C1083: Cannot open include file: 'd3dx9.h': No such file or directory
1> DirectX.cpp
1>c:\users\jake\desktop\whit's base\cabase\Files.h(15): fatal error C1083: Cannot open include file: 'd3dx9.h': No such file or directory
1> Menu.cpp
1>c:\users\jake\desktop\whit's base\cabase\Files.h(15): fatal error C1083: Cannot open include file: 'd3dx9.h': No such file or directory

-PLEASE-
dont troll me for this if it's simple , i'm using microsoft visual basics 2010 express.