Twitter OAuth in Flex 4 web application

I want to use Twitter OAuth in my flex 4 web application and post tweets, on click of a button. Pl开发者_开发百科ease suggest some tutorials or steps to be followed for the same. Also I need to know where should I place the twitter cross domain xml file

You should start with, to undestand how twitter works: http://dev.twitter.com/

Then you need a Twitter AS3 API, which you can find here: http://wiki.swfjunkie.com/tweetr There are some tutorials and examples.