1. Make sure you've extracted a copy of Tomcat somewhere, and that you've populated its bin/setenv.sh with at least export JAVA_HOME=/location-of-java & export CATALINA_OPTS="java+tomcat variables" for your environment.
2. adduser -r tomcat
3. Edit /etc/systemd/system/tomcat.service with the following. Make sure you adjust the paths in ExecStart + ExecStop accordingly.
Description=Apache Tomcat Web Application Container
4. systemctl enable tomcat && systemctl start tomcat
You can get the status of the instance by running systemctl status tomcat -l , and use the "stop" clause to stop the instance.