Displaying a short URL for a website

I am not clear on how to frame my question. I am making the website for my college fest, and although I know HTML, CSS, I don't know anything of PHP. I just want to display my URLs like this:-

http://ift.tt/21B1jru (something like that)

instead of :-

http://ift.tt/21Gh4Kq

How do I do that? Thanks for any help. I am new to all this

edit: I have tried something like this, just removed the constraint-

<script> 
  setTimeout (function () {
    if (typeof history.pushState === "function") {
      var width = window.innerWidth || screen.width; 
      if (width < 768) {
        history.pushState(null, null, "/short-url"); 
      } 
    } 
  }, 10 ); 
</script>

Didn't work. The console gave an error "Failed to load resource" for a lot of files.