Impersonate Permission On Upload

When I use the upload file I get the following error message:

The following error occurred: Can't open file for writing.

I understand this to be because of permissions for the directory. I have looked at the user guide for the script and it mentions this problem and say that you can temporaraly impersonate user while the script is being run and then change back to the default afterwards. It says in the user guide to add the following lines:

UploadObject.ImpersonateUser(UserName As String, Password As String, [Domain As String], [Type As Long = 2])

UploadObject.ImpersonationTerminate()

My question is where in the following code do I need to put this and does this not open up the possibility for someone to get hold of my user name and password. Code: