I need a few made, and i don't mind buying them, but I'm just curious as to how people make them? Is it all php or coding or something like that? Or is it made in flash or something like that?

I'm clueless.

Thanks in advance to whoever can help me out.

They're all basically javascript/php/ajax powered (depends on exactly what you want to do, and who wrote the code). There are plenty of sites where you can just install them instead of creating one yourself. Just do a google search and I'm sure you'll find some xD

Do you mean a Guest counter? or do you mean A countdowner lol