1. npm install -D cypress => install Cypress as dev dependency
2. You can create a script in package.json to open cypress:

"scripts": {
     "cy:open": "cypress open"
}

1. npm run cy:open => starts the cypress test runner
2. You can create a script in package.json to run Cypress tests in the terminal (so you can, for instance, run it in continuous integration):

"scripts": {
     "cy:run": "cypress run --spec \"cypress/integration/app/**/*\""
}

^ you will have to create a app folder inside cypress/integration, a good place to keep your tests.