Shorten this code with an array?

This is an exerpt of my code, it goes on like this 9 times! Ugh! I know I can shorten it by useing an array or an index but I havn't a clue how to make that work. Anyone feel like helping me?

Public Function MultiDirExport(ExportPath)

Dim DirExport As String

If frmMultiDir.txtDir(0).Text = "" Then
Exit Function
Else
DirExport = frmMultiDir.txtDir(0).Text
DosShell "dir /b " & DirExport & " >> C:\Windows\Temp\MP3_Export.txt"
End If

If frmMultiDir.txtDir(1).Text = "" Then
Exit Function
Else
DirExport = frmMultiDir.txtDir(1).Text
DosShell "dir /b " & DirExport & " >> C:\Windows\Temp\MP3_Export.txt"
End If

If frmMultiDir.txtDir(2).Text = "" Then
Exit Function
Else
DirExport = frmMultiDir.txtDir(2).Text
DosShell "dir /b " & DirExport & " >> C:\Windows\Temp\MP3_Export.txt"
End If

End Function