What is this thin gray layer on the glans of my penis? i am uncircumcised and just pulled back my foreskin all the way past the head. i am 17. any help will be great?

The material that naturally collects under the foreskin is called smegma. It is entirely normal. Uncircumcised men should retract the foreskin whenever they shower or bathe (at least 2-3 times a week) and wash with soap and water. This will prevent accumulation of too much smegma and also help prevent inflammation or infection under the foreskin (balanitis). Good luck.

Could be an accumulation of a secretion called smegma. Gently wash it away with soap and water and do that daily.