Error setting user name for Git

What do you want to solve

Step in the above screenshot: I'm learning to add a username to Git, and I'm typing $git config --global user.username in the terminal, but I get an error.

Problems/errors encountered

As you can see in the second line from the bottom of the screenshot, zsh:parse error near `\n' appears and you cannot add a username to Git.

What I tried myself

I searched Google to find out what this error was, but I couldn't get a clear answer, so I asked this question.If anyone knows, please tell me how to deal with it.