what is a podcast and how does one create it?

The simplest way is to record yourself on a smartphone voice recording app like Smart Recorder but you likely want something with better sound especially if you are creating something longer like an audio drama. Smart Voice works well enough when I record a something for The 100 Word Stories weekly challenge. Contributing to an existing podcast can be a way to start.  

There are podcasts about podcasting like Audacity to Podcast  which talks about using the free software Audacity and podcasting in general.I am a fan of podcasts but have not done one. I love the high quality audio dramas and story podcasts I can find. Not that I don't also listen to some about geek news and writing.  

It is basically a video you create, usually by videotaping yourself while you talk. They you need to find a way to upload it so other people can download it or watch it online.