First you should learn this about on HTML5 about the syntax that import audio/ video .Then you should first upload your audio/ video in Dropbox, upload win & google drive etc then you can copy the link of of uploaded audio/video .
[Yes. First complete the course.]
You need to upload file to a cloud site like Dropbox, if your file is in your mobile. It won't access local storage.. So upload and then copy that link and paste as src value.
To know how upload and import to Program...
Run this code and see steps to follow:
For images :
For all files :