You need a bigger peep. Centering your pin guard inside of your peep will give much better accuracy than trying to center just a pin. Centering a single pin means moving your anchor point for each shot at different distances - not good.
Also, move your peep so you have a full view when you're solid in your anchor point. As you draw your bow and hit your anchor, your peep should be there, period.
There is way too much to teach and learn about archery to compact it into your first lesson at a bow purchase. Don't blame anyone, just learn all you can and move on. Change your gear as you need to and when you can afford it.