Hi Suraj,
Look at Twitter’s REST API documentation for the calls you want to make to Twitter. If you want your job postings to be tweeted by an account, use statuses/update.json, which is in the Tweets category. Also, look in the documentation for OAuth because your queries must be authenticated. It sounds like you can use Single User Authentication, which means you can get all your tokens from your application account and perform authentication without user interaction. An easier route would be to use a 3rd party library, like LINQ to Twitter (http://linqtotwitter.codeplex.com/), an open-source library that I wrote, or one of the other packages listed in the Libraries page of the documentation.
Joe