Hi @InqPrice,
at first welcome it's a pleasure to have you between us!
About your needs let me understand: your problem is to identify what to search in your logs or how to search in your logs?
if your need is what to search, the best approach is to search in the firewalls documentation error or special conditions to search in Splunk, remember that to do a job in Splunk: 70% is the knowledge of the technology to monitor and 30% is the Splunk knowledge.
I don't know which firewall technologies you have, probably someone of them already have specific apps and you can start from them in your analysis, so try to search in splunkbase (apps.splunk.com) and define with your firewall specialists the Use Cases to implement.
Another ides is to use Google to search questions in our Community about your technologies.
If you need is instead how to search in your logs, Splunk share training and tutorials (some for free and some for a fee), these are some initial free examples:
https://docs.splunk.com/Documentation/Splunk/8.2.0/SearchTutorial/WelcometotheSearchTutorial
https://www.splunk.com/en_us/training/free-courses/splunk-fundamentals-1.html
and many videos on YouTube.
Ciao.
Giuseppe
