The link you have to make to share something to Twitter is quite simple:
http://twitter.com/share?text=text goes here
But getting a URL and hastag in there is a different matter. To be honest most developers do know how to include the URL, but hashtags have proved more elusive!
http://twitter.com/share?text=text goes here&url=http://url goes here&hashtags=hashtag1,hashtag2,hashtag3
Here’s an example to try out:
And that’s it!