[twitter-dev] Beginner question : How to get the user ID after "authorize" OAuth step?

[Pitt]

Hi,
I'm trying to implement a browser app and Im just blocking at the
first step...
After the user granted the access to his data (OAuth authorize step),
I want to get the user's profile (users/show) but I don't know how to
recover the user's id or screen_name...
Sorry if I missed something in the API documentation but I really
searched...
...And thank you in advance! :)
Pitt