First of all you should start checking that you've NPM and node installed into your machine, to know that type the following commands into the terminal:
$ node -v
$ npm -v
Now that we check that you've got your package manager isntalled you can proceed with the package structure creation for your project:
$ npm init
To install dependencies on your project with npm:
$ npm i <dependency name>
To install a dev dependency on your project:
$ npm i <dependency name> --save-dev