Using Selectors In Nightmare js

I'm still pretty new at automated testing, and I'm trying to write tests for my company.

My biggest problem here is using selectors. I can't seem to figure out how to use them for my purposes.

It's super easy for me to use ID's, like .click('#example'), but we usually don't use id="example" in our CSS.

To start, I'm trying to make it fill out the "first name" input in a form on our site. Here's my code:

const Nightmare = require('nightmare') const nightmare = Nightmare({ show: true })

const Nightmare = require('nightmare')
const nightmare = Nightmare({ show: true })

nightmare
  .goto('https://activeforskolinplan.com/lim-f-i/home')
  .wait(5000)
  .click('.firstName')
  .type('.firstName', 'TEST')
  .wait(5000)
  .evaluate(() => document.querySelector(5000).href)
  .end()
  .then(console.log)
  .catch(error => {
    console.error('Search failed:', error)
  })

The '.firstName' selector in this test is the input classified as name="firstName" in our code.

But in my terminal, it's always saying it "can't find the selector .firstName"

What am I doing wrong here? What can I be doing better?