Autorised by Twitter application only once


I am developing one application. where I need to provide the feature to post a message on twitter after login. users need to authorize using their twitter account only once. after thar some authentication code / token will be store in DB for future action

To do this which API do I need to be used ??

I have used ( API to authorize the user for the first time. it will return oauth_token and oauth_verifier

How can I use these two parameters to post the message on Twitter for any authorized user (authorized previously) ??

Please let me know