The first thing that you need to do is to go and stand in front of the mirror. Make sure you find yourself a good, comfortable spot, as there is a strong likelihood that you would be spending a lot of time in front of the mirror while learning to lift on eyebrow up. Make sure that the room you are standing in is well-lit, so that you can see your reflection clearly.
Raise the eyebrow of your dominant side, which is the right side of the body for most people, and tape it in that raised position. You will be practicing to raise the eyebrow correlating to your dominant side because a person has more control over their dominant side of the body than the other.
Once you have taped your eyebrow in the raised position, trace your finger along it to get the feel of the muscles that are in use. You will be able to tell them apart from the other muscles because they will feel taut.
After isolating the muscles that are responsible for raising the eyebrow, remove the tape from your eyebrow and let it return to its normal position.
Now concentrate on raising your eyebrow by using the very muscles that you discovered in the third step as being responsible for it.
Once you have learned to raise the eyebrow using the right set of muscles, practice holding it in that position for as long as you wish. This will indeed require a great deal of practice, which is exactly why you should be willing to commit a considerable amount of time to your practice sessions. Take breaks if you start feeling tired or discouraged after constant failures.
After you have learnt to raise the eyebrow of your dominant side, start learning to lift the other eyebrow as well. This will increase your range of facial expressions even further.