I don't think that this web site is intended for questions like how to make a dog tag, a pencil, a window, a car, a tree, etc.
I call that being lazy, sorry
There is Google Images (I had hundreds of hits when I typed in dog tag!) and there are things called eyes, brains and hands.
Why don't you use them first before you start asking how to start.
I'm pretty sure that lots of people think like me (they just keep it to themselves). Just start with your dog tag and come back when you're stuck; it's the only way to learn Photoshop and graphics in general and not by reading an instruction book that describes how to make any human made object on this planet or to ask others how to do it for you...