How to install a Raspberry Pi operating system on an SD card
Before you start, you (obviously) should have a microSD card and a computer with an SD card reader.

SD card

SD card reader
Step 1:
Now you should download the latest version of Raspberry pi from its official website here.
Step 2:
Note: the Raspbian with Raspberry Pi Desktop image contained in the ZIP archive is over 4GB in size and uses the ZIP64 format. To uncompress the archive, a unzip tool that supports ZIP64 is required. The following zip tools support ZIP64:
- 7-Zip (Windows)
- The Unarchiver (Mac)
- Unzip (Linux)
Step 3:
Now you should download software which allows you to write on your SD card.
- Download balenaEtcher and install it.
Step 4:
Writing an image to the SD card
- Connect an SD card reader with the SD card inside.
- Open balenaEtcher and select from your hard drive the Raspberry Pi .img or .zip file you wish to write to the SD card.
- Select the SD card you wish to write your image to.
In this video, you can see the following steps.