
The issue you will find is that, indeed you will first need to get acquainted with all these wordings (I agree, they are confusing at first) in order to build something that will work. It's a steep learning curve, and it is difficult (for everyone) to get into this the first time.
Have you studied the photon sample provided with PlayMaker? This is the simplest examples of a working multi player game, it can really be less involving and weird names

I am not saying it's obvious, far from it.
What kind of Data do you want to send from one computer to another? do you mean really building a multi player or do you need to send simple things like scores, or a message?
So, in order to do something useful for you, we need to cut down on the task, otherwise it's going to be overwelhming.
1: How to establish connection ( not sending data yet, just connecting two players together
2: Instantiating players
3: Sending events ( think of features like chats)
What would like to talk about first?
Bye,
Jean