The fuller answer
At birth the foreskin is attached to the glans, and separation happens gradually over years. Some boys can retract earlier and others later. Retraction should never be forced, because tearing can cause pain, bleeding, scarring, and future tightness.
Once the foreskin moves back comfortably, the person can gently rinse underneath with warm water and return the foreskin to its normal forward position. Smegma is a collection of skin cells and oils; small white pearls before full separation can be normal.
Tightness deserves care when it causes repeated pain, infection, scarring, painful erections, or urinary obstruction. A foreskin pulled back and stuck behind the glans is paraphimosis and needs emergency care.