Need help transfering website

So I pretty much have a noob question.
I sold my website on Flippa and now need to transfer the website files and domain to the buyer.
But I am not sure on how to do that.
The other buyer that sold me the website set the site up for me so I just needed to manage the site and now I am a bit clueless on how to transfer my website to the new buyer.
Where do I start? I have the domain on Godaddy so I guess I will have to push the domain from my account to his account. And the website is on Hostgator so I guess I will have to download the complete site from the cpanel as a backup zip where all the files are in it and send the zip to the buyer. That's my educated guess ^^ never sold or transfered a website so help a brother out please ;-)
First push the domain to the buyer and then download the files or how do you guys do it? And do I have to notify Hostgator that I took the website down from the server? Because I am obviously not going to pay for the hosting anymore after I sold the website.

Thanks!

this can help
https://support.flippa.com/entries/21929808-How-Can-I-Transfer-my-WordPress-Site-to-its-New-Owner-

or get someone on fiverr to do it

Thanks, I will look into it.

I which plateform your site in developed, WordPress or HTML/CSS?

do let me know bro ... even i need to transfer my domain name from godaddy

Buddy I can do it! $10, will it works out for you?