No, it's not clear what you mean and you have the wrong definition of derogatory.
Student or Learner
Is it correct to say "He made him look down upon himself or "Derogatory" means to make somebody look down upon theirselves"?
It means to insult someone. So does it have any meaning "Make someone look down upon thenselves or himself"?
Do you mean 'make someone lose his/her self-respect'?
Not a teacher.
No one else can make you look down on yourself.
If someone insults you by saying derogatory things about you, your family, your house, you job, etcetera, that person may look down on you or they may just be jealous. But whether you feel amused, angry, or sad about their comments is up to you.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
If somebody makes you believe that, you are not worth it then he or she can make you "Look down on yourself". What does it mean exactly?
You don't seem to understand what "to look down on someone" means. It means to look at someone as if they are inferior to you. In order to look down on someone, you must feel some sense of superiority over that person. Consequently, you can't "look down on yourself" because you would be suggesting that you are superior and inferior to yourself at the same time.
It's possible for you to "feel down about yourself" - that means that you feel disappointed or depressed about your life or your actions.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.