Apparently, the President first violated the Constitution by promoting a reform to allow the reelection. He said he was just consulting the people but it still sounds like promotion to me.
Both the Supreme Court and the Congress ordered him to stop, but he went forward anyway.
Previously, he also fired the Commander of the Armed Forces, then he received an order of the Supreme Court to put the guy back in his job, but the President refused to do so.
The thing is:
The Congress and the Supreme Court said, “Let’s get rid of Zelaya”, and ordered the Armed Forces to take the guy out of the country. That also violates the Constitution, because he wasn’t taken to trial, and he was expelled of the country when that doesn’t even exist as a sentence.
This is a nice summary of different articles in English
http://www.dailykos.com/storyonly/2009/6/29/748040/-Updated:-You-are-wrong-about-Honduras.
More detailed information can be found in local newspapers in Spanish, in the internet OC.