Well, given that the whole points of servlets is to create a web app, if your apps are going to have user interfaces you'll need to learn at least the basics of HTML5 before you can do anything useful. Also, be aware that you'll need JSP to create the views to front your servlets (generating HTML in the servlet itself is not a good idea).
The second may be a bit advanced if you are just starting out to learn servlets, but it might be a good idea to read through it and gather what you can and get an overview of how to properly structure Java web applications. Then, at a later date, you can revisit it again to understand the details.
Thanks Dave for your input, I want to show how to do this to students who are in programming class.
They were asking how to learn web app development with Java, and I showed them a you-tube video .
Now the students are excited!
I have experience on setting up MAMP on Win 10, but never had to install Tomcat.
I just wanted to get the skinny on this topic.
Learning starts with a question and continues with a discovery Stay hungry for knowledge.