I worked it out: You have to use chrome (ie 11 and firefox do not work they go grey and hang or other strange bugs crop up), and you have to fiddle around because you will find it hard to edit the "Target Folder".
But go to your admin console (remember default username is "admin" and default password is "password")
Then click on network, then click on web server.
Then you enable the web server and point it at a directory you have created inside your main share (you do not need to create a new root folder). Eg I created \\NAS1\share\weberver.
If you can not get the drop down box to work on the target folder then go to the php.ini setup further down the page and restore the default settings, after i did that I was able to edit the target folder box at the top.
My NAS1 IP address is 192.168.5.10, and after enabling the webserver then:
I can type \\192.168.5.10:81 in my browser
and it picks up the index.php file which was created when you setup the web server at \\NAS1\share\weberver\htdocs\index.php.
So to get my web site working I then I deleted \\NAS1\share\weberver\htdocs\index.php and I coped my web site to \\NAS1\share\weberver\htdocs
And now when I type in \\192.168.5.10:81 it picks up my web site file \\NAS1\share\weberver\htdocs\index.htm
All done