Can someone explain me how does sites like mashable.com or gizmodo.com or some other similar sites find all of that fresh news and content? I really don't believe that they write all of that. I mean how they can know every new gadget and on top of that they explain how it works etc etc. I am starting similar blog to these but I am confused about the articles. Thanks.
Read Mashable's about page. http://mashable.com/about/ These are huge businesses with large staffs of people. Yes, they write all of it, but no, it's not done by one guy. A personal blog run by one person is much more difficult to regularly post news. What exactly do you want to do with your blog?
Ajwalsh said it right. If you looking to post fresh news then you must work like a corporate. A separate media team will collect the news and the blogger team will post in your blog.