Importing and Exporting with a macro

I need to create a macro that will process every subfolder in a folder and import the 4 png files in each subfolder, arrange the 4 files as a collage, then export as a transparent png file. I have code to where i can get the file names from the subfolders. I'm stuck on how to import and export them. I assume I can record a macro for the arranging of the files and place inside my code.

Here is my code so far(I found most of it on these forums)

Option Explicit

Public Sub test()
ProcessFolder "o:\temp\navyratesWfolder\navyratesCollage"
End Sub

Private Sub EnumSubFolders(ByVal SrcFolder As String, ByVal Folders As Collection)
Dim f As String

f = Dir(SrcFolder & "\*.*", vbDirectory)

While f <> ""
If f <> "." And f <> ".." And (GetAttr(SrcFolder & "\" & f) And vbDirectory) <> 0 Then
Folders.Add SrcFolder & "\" & f
End If
f = Dir()
Wend
End Sub

Private Sub ProcessFolder(ByVal SrcFolder As String)
Dim f As String, sFolder As Variant
Dim Folders As New Collection
Dim n As Long

' Create a list of folders and subfolders
EnumSubFolders SrcFolder, Folders

n = 1
While n <= Folders.Count
EnumSubFolders Folders(n), Folders
n = n + 1
Wend

' Process the png files in each of the folders found
For Each sFolder In Folders
' You have the subfolder info here in sFolder
MsgBox sFolder
' this gathers files in subfolder that matches the patter inside the ()
f = Dir(sFolder & "\*.png")
'This processes each file
While f <> ""
ProcessFile sFolder & "\" & f
f = Dir()
Wend
Next sFolder
End Sub

Private Sub ProcessFile(ByVal sFile As String)
MsgBox "test" + sFile
End Sub