To Install Google Playstore in android smartphone you have to follow the below steps

  1. Let your android operating system allow to install from unknown Sources, you can do it in Settings > Security, check the box beside to unknown sources options.
  2. Download Google play store for your smart mobile phone| Android Mobile Phone.
  3. May be you can view a warning popup "this type of file can harm your device.” please disregards it if you want to install Google Playstore into your android smartphone and just press OK.
  4. Open the Google play store App or APK which you had downloaded and press Install button.
  5. Here you had finally Install Google Playstore in your android operating system.
  6. Please don't forget last step to uncheck the unknown sources option (what you have done in step 1) after you had completed with the Installation process on your Android Mobile Phone