What projector is it?
Have you checked the manual?
It should be stated in the manual for the specific projector you have.
This question is impossible to answer without knowing anything about your projector, your room, your screen, what you are mounting it on, distance, etc., etc., etc.
Also it would be helpful to write in the title what your issue is rather than just "Need help". It's obvious you need help, otherwise you wouldn't write on this forum. A title such as "How do I properly set up projector" would make more sense.