how to make the background image appear aa when I write the md file

![image](https://github.com/elitistsnob/typora-cobalt-theme/assets/72090328/b33e2d0c-71c7-47c4-8ff8-76c88b97b6ea)
![image](https://github.com/elitistsnob/typora-cobalt-theme/assets/72090328/ded4cc84-9a3c-463f-bd99-8fe8ba8655b0)
I want the astronaut picture to appear as the background when I write the md file