The way to find out is to click on your pins. If they go to the pages where the actual picture and/or article is, then it's pinned from the original source. If not, for example, if they go to a blog homepage or a website where you would have to search for the picture, or if they go only to the picture itself, or my other pet peeve, a site that only has pictures from pinterest and NO original content, then it's not pinned from the original source. If I'm pinning a recipe I make sure my pin leads directly to that recipe. If I'm pinning a tutorial I make sure it leads to the actual tutorial.
To pin you can do it one of two ways. You can go here:
https://help.pinterest.com/entries/2...-Pin-It-button and follow the instructions to add the pin-it button to your browser. Or you can simply click on the + sign on the pinterest homepage (next to your username in the upper right), choose 'add from a website' and add the url manually.