How Do I Display My React Application on the LocalHost after making revisions?

Good evening,

I have been learning Front End Web Development with React through Coursera.org. While I have part of one foot inside the door with the knowledge of web design I acquired previously through Coursera.org, React is all new to me.

Somehow through a lot of trial and error and watching over and over again the videos of the lectures on how to install the react app, I managed to display the react app at the beginning. But the webpage was blank it did not have any design or text in it. Once I started to add the code that the professor was providing us in the videos, everytime I saved the changes and checked the localhost, it kept displaying an error page. When I completed the first assignment, of course the my React app was not displaying, but I passed the assignment.

Now I am on my second assignment and I need to see if what my professor wants me to display on the React app through the instructions given displays. I need to see whether the code that I research and the revisions that will make as a result of the research is correct. Right now I feel I am blinded because i cannot see if whatever code I try works.

What I am planning to do for this Assignment 2 is go over the lectures prior to Assignment 1 so that I can try to reinstall the app and also pin point what is wrong with the code I submitted in Assignment 1. But also I can only assume that I must have made a lot of mistakes copying the code the professor gave me in the videos from the first week of lessons.

Right now, I do not have a working React App.

Any suggestions are greatly appreciated.

Millie