Get a Glute Lift
There are all sorts of fancy moves I could throw at you, but the time-honoured basics are going to work if you stick with them. That means doing them twice a week, with challenging weights and making sure your alignment and range of movement is both SAFE and effective.
I highly recommend getting a trainer to help you with weight selection, then observing the way you carry out the moves to ensure you are getting the most out of your time.
Deadlifts. Heels are just outside your hips, shoulders back and chest open. Holding the bar just outside your thighs, take your hips back as the bar slides down your legs as far as you can without shrugging the shoulders forward. Squeeze through your glutes and press your heels into the floor as you come back up.
Knee raise. No equipment required! Knees are positioned under each hip and palms under the shoulders. Keep your head and neck in a straight line with your spine. Raise the knee, maintaining a 90 degree bend and focusing on using your glute rather than kicking the heel up. Repeat 15 - 20 times, swap sides and repeat twice more!
Stretch. This picture is pretty self-explanatory. Make sure you sit up really tall, like your spine is a steel rod! Hold for 1 - 2 minutes.