I've spent several hours working on this and now understand what the problem is. The issue deals with the namespace MyFirstWebPart.MyFirstWebPart within the code. I was able to first create a blank web part and then after that create a web part with the author's code to get this working.
I'm glad it was just this that was the issue as the community recommended creating a strong name for the assembly, opening up the web.config file to add a new safecontrol line item, and then finally adding the assembly to the gac. As this is my first experience with web parts, it seemed to require a lot more steps for something that you shouldn't have to think twice about.