Range.InsertAutoText (Word)

Attempts to match the text in the specified range or the text surrounding the range with an existing AutoText entry name.

If Word finds a match, InsertAutoText inserts the AutoText entry to replace that text. If Word cannot find a match, an error occurs. You can use the Insert method with an AutoTextEntry object to insert a specific AutoText entry.

Documents.Add 
Selection.TypeText "Best w" 
Selection.Range.InsertAutoText