How to fix errors when trying to make a server using the command parcel ./src/index.html

Question

I'm very new to coding and I am trying to make a host server. (I am trying to learn ThreeJS). When I use the command I get an error message saying command parcel not found the only other thing that I found that might've helped was writing npx before the command that makes the server but it fails straight after. And give an error message saying a specific file was not found. Also I tryed doing the same command on bash and zsh.

Specifics: I entered the code parcel ./src/index.htmlWhen I do this I get the - message bash: parcel: command not found. When I enter npx parcel ./src/index.html I recieve the message: Server running at http://localhost:1234 🚨 Build failed.

unknown: Entry /Users/(my full name)/Desktop/ThreeJsFolder/src/index.html does not exist.

Normally it should make a server like shown above but without it failing like it did.