I'm wondering is it possible and what would I need besides a ethernet shield to make a Web Server w/login user name and password control? I'm looking to turn on/off a few devices. Would I need java or could that be written in html?
You don't need any other hardware but you need to write software for it. On an Arduino you certainly don't need to write anything in Java and to be picky, the standard authentication is part of the HTTP protocol and where HTML is a standard for displaying a page.
I suggest you start with a web server sketch (without authentication) and as soon as that runs and does what you want it to do, come back here, post your (working) sketch and ask for help with the authentication feature. Don't put your expectations too high, you cannot expect advanced authentication features from a computer with 2kB RAM and 32kB storage space.