APEX

Hi.
I am a complete beginner with apex. I am trying to work out how users can log in to an existing apex application.

The login button on the login page has a "Button Request" of "LOGIN".

The Login page has a "page process" of "Login" which has a "source" of

wwv_flow_custom_auth_std.login(
P_UNAME => :P101_USERNAME,
P_PASSWORD => :P101_PASSWORD,
P_SESSION_ID => v('APP_SESSION'),
P_FLOW_PAGE => :APP_ID||':7'
);

now im not sure what LOGIN on the button request is pointing to (my best guess is the page process above but I am probably totally wrong) and i am not sure what wwv_flow_custom_auth_std.login would be refering to.

Perhaps something in the database? or maybe something in the set up of the apex application?

Any help would be greatly appreciated.

Thanks in advance