Acne is very common problem at your age and it is mainly due to hormone and some other factors like diet,bacteria,etc.There are different grades of acne and treatment depends on that.
First stage of acne treatment is for active pimples and then we can treat dark spots and scars.
Next Steps
Its always better to consult a dermatologist and get the assessment done for best treatment plan and better outcome.
Health Tips
Avoid touching or picking your pimples as it can leave dark spots and scars if pimples rupture. Clean gently and do not scrub with towel. Avoid home based remedies.
Go through my article on acne in detail where I have mentioned treatment plan as per stage and also some other tips.