Changing password on guestbook 1.5

Hi,

Changing password in guestbook 1.5

Please could someone help, my friend set the guestbook up for me but I need to change the password. I would imagine I can do this within the admin section but don't know how. I'd be really grateful if someone could give me some advice on how to do it.

Many thanks,
Garry

I do believe that the password is actually in the file.