After you downloaded Raspbian OS from https://www.raspberrypi.org and extract zip file to .img file. Right now you must write the .img file to your MicroSD Card. We recommend you write .img file with Etcher program.
1. Download Etcher from https://www.balena.io/etcher/ and then install it.
2. When you finished install Etcher please prepare your MicroSD Card and plugin to PC card reader. After that you check MicroSD Card working or not on your PC. If your computer shows up the new drive with removable it’s mean your PC was found your MicroSD Card right now you ready to flash Raspbian OS to MicroSD Card.
3. Open Etcher and click on “Select image” button and click on “Flash” button. Wait until flash image finish you will get your Raspbian OS on your MicroSD Card
4. When your finished flash Raspbian OS don’t forget remove your MicroSD Card from the card reader and now you ready to Boot up your Raspbian OS from your Raspberry Pi.