HTML. Make Website Fit Other Devices And Screens?

I recently got "done" with a website (http://ift.tt/28ZWMsj). It looks fine on my screen, but on my friends' screen it does not fit the screen. The same with my other devices. I have added this to the Head tag:

<meta name="apple-mobile-web-app-capable" content="yes">
<meta content="text/html; charset=utf-8" http-equiv="content-type">
<meta name="viewport" content="width=device-width, intial-scale=1">

I have heard many people saying "that will fix the problem", but it didn't i don't even know what it means. Were them lying? How would i make my website fit any device and screens?

Thanks you. :)