backup for newbies

Define “easy”…
Good tutorial: https://codex.www.ads-software.com/Backing_Up_Your_Database

That’s a good tutorial – if like me you’re not an expert with php, I’d recomend the Backup Plugin (scroll down the page). It’s easy, latest version is here:
https://www.ilfilosofo.com/blog/wp-db-backup

This backs up your database – your posts, comments, and so on. It doesn’t back up your theme pages – index.php, style.php, and so on. So if you’ve made any changes like adding things to the sidebar or altering the theme, you’ll need to back them up too by downloading them using your FTP program.

Okay, so now that I have the backup file saved on my computer, have changed web hosts and totally reinstalled WordPress 2.2.1, plugins and everything, what do I do with this backup file? Where do I upload it?

Use the BackUpWordPress plugin:

https://wordpress.designpraxis.at/plugins/backupwordpress/