To create news aggregator site you need to use RSS feed technology to extract data (texts, pictures and videos) on a specific topic from different web sites and publish that data on a single website. Such web site needs quality web hosting, start with VPS (virtual private server), get a professional news aggregator theme, find what aggregator plugin fits you best. And very important - content. What your web site will be about? What sites will you use to pull content from? Make these content sortable, be creative and add your personal touch to the way you wrap it. WordPress platform gives you many ways to achieve this goal.