Hi there Frank.
It is genuinely amazing to see VTT platforms being used in such a manner, kudos to you!
As a first time user of Foundry and Forge I would recommend you to go through our getting started Index as it covers most if not all questions one may have with, well, getting started.
Regarding modules, there are many, many modules to pick from to tailor the game to your needs, most of them are made by Foundry community members and are free, some are one time purchases such as asset packs, others require Patreon subscription for their respective creators.
I would recommend you join our Forge Discord channel, and also Foundry Discord channel, there you will find thousands of game masters that can steer you in the right direction in regards to which modules to use and even maybe different systems that might better suit your needs.
Happy gaming!