Ensure that you have created the Windows Phone project in VS. If you can run it on the device then it should work with the following. Taken from this site: http://sviluppomobile.blogspot.cz/2013/03/how-to-debug-windows-phone-html5-apps.html
You can verify if the server started by opening a browser page and
loading 127.0.01:8080 (8080 is the default port for Weinre). If you
are seeing this page then the server is running:
Now click on the Debug Client User Interface link where you will be
able to see if any client is connected and debug the connected
clients. Let's create the Windows Phone HTML5 application. Use the SDK
template to create a new project, open the page index.html inside the
folder Html and add this line to the head section:
<script src="http://[the server
ip]:8080/target/target-script-min.js#anonymous"></script>
replace [the server ip] with the IP of the PC running the Winre server
and run the application. If everything went as we expected in the
Debug Client user Interface on the Server we should see one Target
connected:
Once the target Windows Phone page is connected you can inspect and
change the DOM in real-time
Failing that you can always run the site in IE11 and change its settings to emulate a Windows Phone device, then use the inbuilt IE debug tools, but that obviously doesn't debug on the device...