The Glute Bridge is a very effective exercise for training your gluteal muscles.
1. Lie on your back
2. Place your feet hip-width apart and firmly on the ground
3. Build up pressure over your heels
4. Drive your hips up completely, actively squeezing your buttocks in the uppermost position
5. Your shins are 90 degrees to the floor, your body forming a single line
6. Slowly lower your buttocks again, just below the floor, and stretch again