Copy e Read file in the specified dir

hi,
I created a new DIR in dirdefaultexternal

File.MakeDir(File.DirDefaultExternal,"memoBackup")

How do I copy in a specific file
File.Copy(File.DirDefaultExternal,"menom.db", File.DirDefaultExternal,"memoBackup/memobackup.back")
how do I list the specific files in this dir?
List1 = File.ListFiles(..................)
Thank You
Nicola