The headset comes with different-sized earpads. Select the earpad that fits the best. To change the earpad, gently pull the current earpad from the earpiece, and push the new earpad into place.
Gently push the earpiece into your ear.
When you're not using your headset, keep it in the cradle. You can put the cradle in the carry case and use the handy clip to attach the case to something.