Sometimes it's difficult to tell if the information you're looking at is true. In that case, see if you can confirm the information elsewhere. Two reliable sites that look into questionable news and other items online are:
Politifact: "PolitiFact staffers research statements and rate their accuracy on the Truth-O-Meter, from True to False. The most ridiculous falsehoods get the lowest rating, Pants on Fire." More information on Politifact here.
Snopes: This site started out investigating urban legends online, but its scope has grown to include lots of kinds of information online including the news.