Nano is a command line based text editor which comes installed in every Linux system of which I am currently aware. It is relatively easy to use for quick edits.
When you begin this exercise it tells you to run the command:
What this does is open the nano program on a file called hello.txt. If that file already exists, it will open the file. If not, it will create a new file with that name, note the bottom of the screen where it says [ New File ].
With the program open, it wants to you type:
"Hello, I am nano."
It is the same as any other word processor at this point. The answer checks are pretty specific, so make sure to include the quotations.
The biggest difference is the commands. Obviously you can't use the cursor to operate the menu, so you have to use the keyboard.
At the bottom of the screen you see various options with a white highlighted block to the left and the meaning to the right. The ^ means to use the Ctrl key to use that particular command. So you would use Ctrl + O which writes out the file, also known as saving. You simply press the Enter key to confirm the file name, then Ctrl + X to close the file altogether.
Finally, you use the clear command to empty the window. This comes in handy if your terminal window gets cluttered, but is not a truly necessary step in real world applications.
I hope that was helpful in explaining the scenario. If you need additional guidance, let me know exactly what part is holding you up and I will try to address it in more detail.
For practical application, you can just use Ctrl + X and if there are unsaved changes it will ask if you want to save them before closing. It is personal preference on how you want to go about saving, I just prefer one command versus two.