add authentication with only continue/confirm button


I am not that experienced in access manager. But I would like to protect a service with an authentication class that serves as warning text before you access the site (let's call it click2continue).

So, for example, I try to access said application I get this authentication contract which has some text and at the bottom continue button after I click continue authentication should be successful and I should get through the application.

That would ensure that no matter what user has to click to continue/agree before accessing the application, also I could add additional authentication that would truly authenticate users.

If I could ensure click2continue authentication is voided every time user leaves the application, well that would be even better!

Any ideas? I gather I have to write new class, is there some already written alternative?

I am almost certain I will have to write new class, so are there any tips on starting with that?

I would rather learn to write it instead of getting a written solution, but if I get latter I would probably reverse engineer it...

Thanks to everyone taking the time