Google app for domain only

[St.e]

I don't know a lot about Google Apps Engine or Java,

but I chose to use it because it's the only way to finish my project.

(which is due in a couple of days)

I created a new application,

with authentication option: restricted to a Google App domain

I uploaded my application (a html page with javascript) with Eclipse (for Mac)

I added it as a service on the Google Apps domain

But it's still viewable for everyone on the internet.

I know I should do something with the Users Java API, but I don't understand it..

Any help?