Hey i know a way but do you want a Login and password box?

or Just Password cause if you just want a password then if you have hosting you can use the "WEBPROTECT" addon that comes with most hosting companies.

It will password protect a folder i not sure if it will protect certain files if it doesnt then all you do is transfer all you photoalbum files to a new folder called photoalbum then use the "WEBPROTECT" to password protect that folder and then the photo album will be password protected.

But up to you and also you can do it in php like Accurax said and Karinne but up 2 you and cause your a beginner the easiest way for you to do this is "WEBPROTECT" but its your site so up to you how you want it dispalyed

Hope this Helps you for what you wanted?

Thanks
Aaron