Im 13 and my knob hasn't shown
Hi Guest,
If you mean you can't see your glans because it is under your foreskin - NORMAL.
Most guys can't fully retract until around age 16 or so.
You NEED to start stretching your foreskin. Either use your fingers to spread the opening OR get an erection and pull down on the shaft skin so that the glans spreads the opening. It is often easier to do this in the shower as the warm water can help soften the skin.
Take your time, you don't have to hurt yourself. The more often you do this the sooner you'll see results.
Hope it helps.