Wash your new jewelry for 3 minutes with antibacterial soap and hot water. Lather the soap in your hands, and rub the barbell between your palms. Dry it well with a clean paper towel.
Unscrew one bead by twisting it clockwise. Set the bead aside, leaving the other one attached to the barbell.
Rinse your mouth for 30 seconds with antiseptic mouthwash. Spit it into the sink, and rinse your mouth with water if you prefer.
Insert the barbell from above, sliding it gently through your piercing until the bead rests on the top of your tongue. You should see the open end just barely sticking through the bottom of your tongue.
Grasp the tip of your tongue with a clean paper towel. Use the towel to press on the top bead and hold it firmly.
Insert the threads of the bead you removed into the open end of the barbell. Twist counter-clockwise until it is tight. Give both beads a twist to tighten them and secure them firmly in place.