I have multiple eyelid folds and uneven ones, how can I solve this? I'm 21 years old. (photo)

You issue is that you have upper eyelid levator disinsertion ptosis.  It is a bit asymmetric.  Without a clean insertion of the tendon into the eyelid platform, you end up with multiple folds.  You need an anterior levator ptosis surgery and an anchor blepharoplasty.  This will give you a clean upper eyelid fold and a jewel like eye.  I recommend a personal consultation.  Who you see as a surgeon makes a huge difference to the out come of surgery.  You need an aesthetic eyelid specialist and it is definitely worth traveling to see the right surgeon.

You may benefit from very conservative skin only upper blepharoplasty. Volume addition (through filler) may also be beneficial. You should also be evaluated for ptosis. See an oculoplastic specialist.

Thank you for the photo.  You would definitely need an exam to be certain but I see some mild ptosis and multiple weak attachments from the front face of the levator tendon to the under surface of skin.  This is quite common.  I'll provide a link with a similar cases of both ptosis and poorly defined eyelid creases.  See an experienced eyelid surgeon who performs cosmetic and reconstructive surgery of the eyelid.  What you see in yourself is very common.  A good surgeon can help you with this.Chase Lay MD

Multiple eyelid folds  are due to the  multiple attachments of the levator to the skin in that location. A very conservative skin only blepharoplasty can accomplish creating one fold. This can be performed under local anesthesia. Also important to rule out any ptosis that may be present. For more information many examples, please see the link and of the video below

Hello lauxxx!
Your solution is not difficult. Remember less is more. Someone as young As you might open the door up to complications if your not careful with the right  surgeon and correct procedure of choice. Suggestion is to match the crease be adjusting the skin and maybe the height with muscle fixation. Around 30-45 minutes . Cost will vary around $2500-$4000. Please see an Oculoplastic specialist who has extensive experience in this area. You should do just fine. 
Cheers! 

Usually upper lid surgery is usually considered for the correction of aging changes. However, you are too young for aging changes to be preent, being just in the early twenties. It is a variation of the normal to have multiple skin pleats in the place of a single lid fold. Some attractive models have this appearance, but it is not as attractive as having a single lid fold, and the look does not improve over time, in fact it deteriorates.Most plastic surgeons would be reluctant to perform lid surgery on a  young person as the situation is not so forgiving and there is the risk of having visiible scars.Surgeons versed in the advanced lid surgery technique called tarsal fixation blepharoplasty do not have this reluctance as the technique does not rely on making the lid skin tight, so there is not tension across the suture line causing the scar to stretch.Correctly performed, that is using internal dissection and internal fixation, the lid contour is changed to the more attractive appearance that most people admire, while the change in the internal anatomy is permanent. It that is the case there is not benefit in waiting to enjoy the benefit of this surgery.