I've been interested in writing my own emulators as well. The hardest and most important part ofcourse, is actually emulating the cpu. If you aren't using someone else's cpu core, you have to make your own. This can definitely take awhile, and will require accurate documents.
So the first thing you should do, in my opinion, is download some cpu cores/emulators made by other people. Then open them up and look through them, try to understand it. You also might want to find some emulator's source code to look through. There is no step by step sort of way to do this, atleast not that I've found.
Also, if you decide to go through with this, definitely try to emulate something that is already emulated and well documented. Forinstance, Space Invaders, Donkey Kong, Pac-Man. Start easy before working your way into harder and more complex things.
Also, there are a few mildly helpful getting started emulating faqs/tutorials out there. Use google to try to find them. I know there is some "Arcade Emulation Howto" which includes a sort of walkthru for making an emulator of the Phoenix arcade game.
> hi guys, im learning on school c++ and delphi, i love emulators since i
> discovered what is internet, now i want your help begin make an emulator i wanna
> know what i have to know and for where begin learn programmin emulator.
> Sory my english is really bad :)