Although this video is about moving your website from Hostgator to WA's hosting, it can actually work for almost every other webhosts out there because basically, we need only to...
1. Back up your files from your webhost
2. Transfer those files here at WA through FileZilla
3. Contact Wealthy Affiliate's support to double check and reconfirm.
Don't worry about FileZilla, you don't have to understand how it works because you'll be only using it just this once to move your website. Wealthy Affiliate makes everything easier for you to handle your website which is why we don't cover the use of FTP clients here as it is very technical.
FileZilla is free to download, and Welshy has even covered the installation part here...
https://my.wealthyaffiliate.com/training/ftp-filezilla-connecting-to-domain-via-ftp
That's it, now you can say goodbye to Hostgator!