hi every one new here i have pc for game one old play stasion1 <---- but now i start download game for my brother but we don't now how to use
So you've downloaded a PS1 game? If you want to play it in your PS1, I think you'll have to mod it somehow, but there are countless PS1 emulators, such as ePSXe, that can run most PS1 games just fine on your computer.
In order to play downloaded Playstation games on your Playstation 1, it needs to be modded or you need a 'swap disc' (special disc that you load first, then change to the downloaded copy). Personally I find it easier to play them on your PC with an emulator. It does not require a very powerful computer, and the Playstation 1 emulators work very well.