Could you please tell me what these lines really are and something I can do to get rid of them? (Photo)

Hi Alisha,
These under eye lines start appearing as we age and loose volume in our face.  It's usually corrected with fillers, a surgical procedure called lower Bleph or with lasers.  Since you are a teenager, none of these would apply to you and I would just start using really good eye creams, plenty of hydration and get more sleep.  That should help a ton.  Good luck, Dr. Onir

Dear alisha_k9:The lines you have noticed under your eyes are known as Dennie-Morgan folds and are due to a little bit of edema. This is common in those individuals  with a personal or family history of atopic dermatitis, keratosis pilaris, hives, asthma, and allergic sinusitis, conjunctivitis, or rhinitis. If you have any allergies or rashes you might want to consult with a dermatologist or allergist for treatment. Applying a strong green-tea polyphenol cream can sometimes reduce the lines by reducing the edema.  Wikipedia has a good entry explaining this sign. Check out this product below if you want to give it a try. All the best, Dr. Clark 

The lines closest to your eye are normal creases/folds of skin that make up your lower eyelid. There is nothing negative or unattractive about that. Don't look  too much into that. The bottom most line or indentation closer to your nose is your tear trough. This is sometimes genetic and also worsens with aging . When this indentation is deep, it can give the appearance of a dark circle  secondary to shadowing. If that bothers you, you can use a concealer with your makeup which as a teenager is usually enough. If you want that gone without makeup you can consider filler.