DEADLIFTS
How it's done?
With barbell
Go stand with feet flat beneath the bar and squat down. Take a grasp on the bar with hands about a shoulder width of the bar, or a little wider. You can do normal or a mixed hand grip. Executing happens by lifting the bar by extending your hips and knees to full extension. Pull your shoulders back at the top of the lift. At the top of the movement you should be almost standing straight. Now bend your knees and hips and go down with the bar almost touching the ground, or if you have weights on your bar the plates can touch a little bit on the ground. One repetition is now executed. Throughout the movement keep your shoulders back and back straight. Again I can't stress to much of the importance of keeping your back straight!
With dumbbells or weight plate
You can do deadlifts also with dumbbells or with a weight plate. Movement is similar to barbell deadlifts, only difference being that you have dumbbells or weight plate in your hands. Depending on your stance keep dumbbells on your sides or perhaps one bigger plate between your legs.
Stand in a shoulder wide stance with dumbbells on your sides in your hands. Keeping your knees straight lower the dumbbells by bending your hips and keep going down until your hamstrings are tight, or until your lower back would start to bend. Keep your back straight during the move at all times! You can also use a weight plate if you do the "feet wider apart" variation.
What it targets
Main target of the basic deadlift is the hamstring, but it also has effect on your gluteus and lower back.
Tips for shaping butt.
Again standing with feet wider apart puts more stress on your buttocks. Deadlift can also be hard on your back remember, especially when your legs are wide apart, keep your back straight! To help this try to look at all times to "horizon".