Are you trying to access Word's AutoCorrect feature via programming?
Look into the AutoCorrect object and the Entries collection. You can use
the Object Browser and (of course) the help file to learn about Word's
object model.
The OP wants to use Word functionality in his own Visual Studio app
(gleaned from yet another posting, this time in the VSTO forum). Which
of course, is not possible. But VS developers are accustomed to
"everything" being in an accessible class library, rather than
confined to an application's UI