Welcome!
I think it might benefit you to get a virtualization 101, even before getting into network virtualization. Here is a starting place: What is virtualization? Virtualization 101 | United States
Then to get started in NV, I would recommend starting with the NSX Fundamentals class. Depending on your location, there may be a live class near you. That would be the best option because you have direct access to the instructors. Otherwise, we constantly deliver them live online as well. There is a technical intro webinar on Wednesday: Registration Launch As a last resort, you can always watch a recorded version of the Fundamentals: VMware Network Virtualization Fundamentals
Hope that helps! Please use the communities to ask questions. There are a lot of super-geeks on here that can answer just about anything you need.
Regards,
Bryan