How do I call assets files like mp3 file or video file using blocks

how can call a file that i upload to the assets like a mp3 file or video ?. or text file??. some tutorial? i would like to assign a number value to create a random display between the file items inside the assets

Show what you have tried so far (your blocks).

Usually files in the assets are read/accessed only with their filename. However, this does not apply to the WebViewer (HTML files), for example.