如何打开一个文件夹并选中指定文件

很简单，调用explorer.exe就可以，例如要打开H:\CD1并且选中其中的readme.rtf：
Private Sub Command1_Click()
Shell "Explorer /select, H:\CD1\readme.rtf", vbNormalFocus
End Sub

[Windows Explorer Switches]
Windows Explorer switches are useful in creating rooted folders:

Explorer [/e][,/root,<object>][[,/select],<sub object>]

/e
Use Explorer view (scope and results pane view). The default is
Open view (results in pane view only).

/root<object>
Specify the object in the "normal" name space that is
used as the root (top level) of this Explorer/Folder (i.e., local
path or UNC name). The default is the Desktop).
/Select
The parent folder opens and the specified object is selected.
<sub object> Specify the folder unless /select is used. The
default is the root.