The best way to know you have scoliosis is by visiting your doctor, a physical therapist or your school nurse as they all have been trained well in diagnosing scoliosis. They may use a device called a scoliometer (like a spirit level) that is helpful in mild cases.
However if you want to check by yourself you can do this Postural self assessment at home here are some signs to look for;

• If one of the shoulder is higher than the other
• If your hip is position more on one side rather than other
• Is you back is slouched and no matter how much you try to sit upright it doesn’t change

You can as well perform the adam’s forward test, it will be helpful to ask you family to check this for you;

1. In standing you will have the other person stand behind you
2. Close both of the legs together, interlock your fingers together
   Bend forwarded as much as you can without your knees bend
3. At this position the person standing behind would be able to see the curve if any present.