Hi,
The topic has steps for setting up HLS:
HLS Live streaming - #4 by DaneLLL
For adding audio, please try
$ gst-launch-1.0 videotestsrc num-buffers=300 is-live=1 ! 'video/x-raw,width=1280,height=720' ! x264enc ! mpegtsmux name=mux ! hlssink audiotestsrc num-buffers=500 is-live=1 ! voaacenc ! mux.