Hi there! Here is a quick step-by-step guide to playing the game:
1) Download it on your computer. Note: Make sure if you have a Windows computer, you download the Windows file. If you have a Mac computer, download the mac file instead. You say you've downloaded it already, so you can skip this step if you downloaded the right one.
2) Go to the downloaded file. It should end with ".zip".
3) Right click on it and "extract" the files. This will create a new folder.
4) Open that new folder and look for the ".exe" file. That's the game! Just double-click it to play.
Good luck and hope this helps! If not, you can detail the problem and I can guide you from there.