Hi Alan,
It can't find index.php because it hasn't been uploaded (along with some other folders/files):
These are the current the contents of your powergallery/install directory:
* 1.php
* 2.php
* 3.php
* 4.php
* css/
* global.php
* images/
It should also contain the following.
* samples
* scripts
* index.php
* 5.php
* 6.php
You must upload ALL the folders and files as directed.
If DreamWeaver is not doing it, you can find a free FTP program to do it.
You will also need to have a database plus details (localhost, DB_UserName, DB User_Password) ready for when you set up power Gallery.