Also did they just cut out a piece of black cloth and hang it? Or was there something more intricate?

We dont have enough surviving evidence to prove how it actually was at the time, but in modern times it is that way because one of the only surviving pirate flags is a jolly roger.

[off topic]

Black Sails

https://www.imdb.com/title/tt2375692/

Better than Pirates of the Caribbean or Game of Thrones.

A black flag actually meant quarter would be given. It was the red ("bloody") flag you had to watch out for. Not sure about how the black flag became known for giving quarter, but the symbolism of the red flag is obvious - and dates back as a symbol of no quarter (on land) to at least the medieval period.

Repairing sails and clothing was a necessary skill for seamen, so making a flag - so long as there wasn't any need for fancy dyes - was no big trouble for sailors-turned-pirates.

If you're asking why it's used as a no quarter symbol today, just the general mythology of the (often exaggerated) viciousness of pirates. Landlubbers and sailors certainly share at least one quality - the love of tall tales!

Does it tell how the black flag came to be? Then used by the common folk?

I think the French Oriflamme was first