In the VBA editor's help, try looking for "files collection".
then, select the entry for the
Files Property (Visual Basic for Applications)

It gives you sample code that looks like:
Sub ShowFileList(folderspec)
Dim fs, f, f1, fc, s
Set fs = CreateObject("Scripting.FileSystemObject")
Set f = fs.GetFolder(folderspec)
Set fc = f.Files
For Each f1 in fc
s = s & f1.name
s = s & vbCrLf
Next
MsgBox s
End Sub

You can modify this code to do what you need to do for each file.