How To Upgrade WordPress Manually?

Argh, how to upgrade WordPress manually?

I know I can google and learn how to upgrade it to the latest version. Indeed, I have already done so.

The problem is that the ways and methods to upgrade are a bit complicated to me. I am scared that I will screw up the database of this blog.

Is there any simplest way to upgrade the WP? Oh, please don’t tell me about the one-click upgrade, okay? The database of this blog was recently moved to another server without moving the add on domain.

Sigh, it’s a long story!