I got a 6 inch training tab for my friend's new puppy and she's never used one before, can you explain how to use it?

A tab is just a short version of a leash so you have something to grab if you need to. For puppies, I use a leash though, because the average puppy needs to be managed a lot and grabbing for a tab is inconvenient and can create a puppy that tries to get away from you when you reach for them. I use them for a dog that is trained as I'm weaning them off of the leash. As the puppy gets a bit larger, it will likely be very handy! Just make sure she watches that the puppy doesn't chew on it.

It's a great and useful piece of equipment but something I use a little later, not usually with brand-new puppies.