Launch IE from metro app and send post data to the website

Question

I want to launch a website in IE from my metro app. While launching the website post data also need to be send.

I tried using Windows.System.Launcher.LaunchUriAsync(uri);

I am facing two issues here. one, i am not able to send post data to the website. Second, the IE is taking only 50% of the screen. I want it to consume the entire screen.

How can i possibly do that?