when i open my file it just hang on loading- 97% (Firefox) and when im on my phone browser nothing shows, while in chrome, it finish the loading but shows all white and says rats webgl hit a snag. what should i do ?

Attached herewith is my file in .html format that i need to open in my browser. please help. Thanks :))

https://www.blend4web.com/en/article/103/

What I did is just change the objects inside the file. I don't change anything in the script or any code in their. but why the WSAD keys is not working ? while the arrows keys and mouse are working (left, right,up and down)

ASDW is not working but my mouse is working . How to solve this ? please help ….

where should I put the code? I don't get it Am I going to open a notepad and place the code there?

I still don't get it :( the shadow.html that you gave @pavel does not shows shadow to me . I followed the video tutorial that you gave but still it does't work . The blender that I used is v2.75