I don't get Pinterest

The other day, I was chastised about the sad state of my Pinterest account...

"I just started following you on Pintrest. I have to say your boards aren't very pintresting at all...add something already! You certainly have a ton of stuff to share!"

I'm not sure that's true though. Mostly because I'm not sure I understand how Pinterest is supposed to work. "Pinterest is a Virtual Pinboard!" is what it says at the site. But what does that mean? I don't even know how I would use a real pinboard, let alone a virtual one. I only signed up a few days ago and since I don't know what I'm doing, as of right now I have one Pinterest board. It's titled "Board" (subtitled "A board upon which one could pin Things" for clarification purposes) and has nothing on it. I'm actually pretty proud of it because it's extremely organized. It's probably the most neat and orderly thing in my life. But I'm clearly doing it wrong.

Here's what I think is supposed to happen...

• I go on line and come across a picture of a dog. Whose dog is it? I don't know. It's not mine. I don't think that matters. Or somebody's cat. Maybe it's my cat. Or a pie. I don't have any pie right now though. Whatever.
• Hey, I like dogs! As well as cats and pies. This picture of an unknown dog pleases me, so I "Pin" it.
• Now this picture of someone else's dog is on my board.
• Other people, whom I may or may not know, can see this picture of someone else's dog on my board.
• One of these people, possibly a complete stranger whom I will never meet in my lifetime, says to themselves, "I also like this picture of a dog that Clark has on his board. I shall Pin it myself."
• This connects that person to me and now we are friends. I guess.

I mean, is that it? I think it is. I'm pretty sure it is. If so, what exactly is the point? I'm not knocking it; I honestly just don't know. I'm aware it's incredibly popular and people talk about it all the time. It's probably me, missing something. So if somebody who gets it wants to give me a class, I'm willing to learn. Especially if you can show me how to use it to shill promote my stuff. 
Thanks in advance.

I wish there was a way to share this photo of my cat Jack making it
difficult to type this very blog post...oh wait a minute!