Alright, first things first, we need to get the Firebase CLI (Command Line Interface) up and running. But before that, make sure you have Node.js installed. Once that's done, just pop open your terminal and type:

npm install -g firebase-tools

Next up, let's log in to your Firebase account. In the terminal, run this command:

firebase login

You'll get some prompts. Just follow along, and you'll be logged in before you know it.

Now, navigate to your project directory. Once you're there, initialize Firebase by running:

firebase init

When the menu pops up, choose the Hosting option. Follow the prompts, and this will set up your project, creating a firebase.json configuration file and a public directory (or whatever directory you choose for public files).

Ready to go live? Make sure all your site files are in the public directory (or the directory you specified earlier). Then, deploy your site with:

firebase deploy

1. Head over to the Firebase Console.
2. Select the project you just deployed.
3. On the left-hand menu, click Hosting.
4. Hit the Connect Domain button.
5. Enter your custom domain and follow the instructions.

Firebase will give you some DNS records to add to your domain registrar’s DNS settings. Here's what you need to do:

1. Log in to your domain registrar's account.
2. Find the DNS settings or DNS management area.
3. Add the DNS records provided by Firebase. Usually, these include A records and maybe TXT or CNAME records.

Head back to the Firebase Console and click on Verify to wrap things up. Keep in mind, it might take a bit for the DNS changes to kick in.

If you need to set up redirects, you can do that in the firebase.json file. This is handy for things like HTTP to HTTPS redirection or other URL mappings.

Example:

"hosting": {
  "redirects": [
    {
      "source": "/example",
      "destination": "/example-page",
      "type": 301
    }
  ]
}

Don't forget to deploy again if you make changes to the firebase.json file by running:

firebase deploy

Once your domain is verified and the DNS changes have propagated, visit your custom domain URL to make sure everything's working smoothly.