To install flash games on the computer, search on Google for some flash games that are available for download. Once your flash game is downloaded you will need to install the Adobe AIR application, which can be downloaded at adobe.com. Once the Adobe AIR is downloaded just double on the executable to install the application.
Once Adobe AIR has been installed, you will need to download the flash player and install that as well and the Adobe flash player is also located on the Adobe website. After the Adobe flash has been installed you will need to go out and find a flash player that is compatible with your operating systems. The flash player recommended for Windows is the SWF file player which can be downloaded here. Once you download the SWF file player, install it and open the application.
Now click on File, open and in the File textbox type in the path to the flash game. For example, if you downloaded the flash game on your Desktop and it is called flashgame.swf you will need to type in C:\Users\username\Desktop\flashgame.swf.
Now click on the Play button at the bottom right you should be able to play the game on your PC. Flash player is usually automatically run on the computer with all of the permission necessary for you to run any thing related to flash but flash has some vulnerability in them that is why if you are using Windows 8 or higher many time Windows will prompt you to give access permission to the player otherwise it would not work. Flash games do not require to be installed on Windows for it to work but other applications like Adobe flash player, Adobe AIR and the SWF file player are required to open the flash files.