Grasp the nut on the right side of the base of the toilet with a wrench.
Twist the nut clockwise until it is tight. Do not tighten the screw with great force, as over-tightening can cause the toilet to crack.
Repeat this process on the left side of the toilet.
Grasp the nuts that hold the tank to the base with a wrench. The nuts are located on the left and right of the underside of the tank.
Twist the nuts clockwise to tighten them until they are secure. Again, do not tighten the nuts with great force.