"url Rewrite" With Iis?

I'm hopeing someone can lend me an hand here

I'm currently running a webapp with its own webserver on port 1234, and its always mapped as /myapp eg <ip adress>:1234/myapp

Now what I want to do is rewrite this using IIS so I instead get <ip adress>/<what ever I want to call it>

I've figured by various guides that I should be using ARR and URL Rewrite plugins, and I've installed thoes 

But further than this I can't seemt to get

Any pointers?

PS: Windows Server 2012 Datacenter, with IIS 8.0