How to run a script on RStudio

Hello, please how do I run a script on RStudio, I am pretty new an still struggling. The instruction says I should open a file, run the script one by one and interpret the analyses. Can anyone please guide me step by step on how to do this? It's urgent I am trying to do an assignment and the deadline is near. Thank you.

Chech this video for you:

You need open the file and practice. Remenber install the software.

Thank you so much. I will check this out now