You'll need to configure and run a web server on your computer. The most commonly used, publicly documented, free and accessible to people just trying stuff out is LAMP). You'll then need to point your domain at the IP address of your server.
Thing is, I have a computer that stays on 24/7
What kind of hardware are we talking about? How much traffic are you looking at supporting? What kind of internet connection do you have at home? Are you familiar with the concept of mathematical multiplication?
Regular home PC, fairly dated at this point. Not much traffic is intended, though - it'll have a fairly quiet home page for my job(I'm not allowed to have more, for tedious reasons of legal compliance in advertising), and a hidden wiki that'll be seen by maybe a dozen friends. It's a toy site, not anything serious.
Re mathematical multiplication, I assume you don't mean 3x4=12. Is this some sort of traffic collision issue?
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