Actually that JW Player tutorial is slightly out-of-date (you can't even get JW version 5 easily anymore at their web site). Might be better to just go to the JW Player site and follow their guide for RTMP/HTML5 using version 6:
I like the second example under "Embedding a Stream" on that page. To modify it a bit for Wowza:
So the steps would be as follows:
1. Verify Wowza's default VOD application, to play the default "sample.mp4" video file -- sounds like you've done this already:
2. Download JW Player:
3. Upload the three files contained in that JW Player download (jwplayer.js, jwplayer.html5.js, jwplayer.flash.swf) to the same folder on your web server.
4. Make a new web page in that same folder with the code I posted above, substituting your Wowza domain name or IP address for "[wowza-address]".
You should now be able to load that page and see the sample video on any Flash-capable browser or iOS device (iPad, iPhone, etc).