I'm new to Wordpress. I have a website that I coded myself. One of the pages has PHP functions that take a google calendar feed (with hard-coded login info) and displays it as needed.
I am now building a new site on wordpress where I want to use the same code. My reading says I should handle this as creating a new plugin so that I don't overwrite it with any theme updates.
My question: how can I simply copy my PHP code into a file in it's own plugin folder and then use a shortcode to access it like an include? Specifically, I don't understand if I am able to use shortcode as an equivalent of