Where and how I can validate, implement my knowledge in health and safety field as NEBOSH holder, whereas all organizations require an experience.?

Apply as trainee or casual employee, after time you gain experience and that company may hire you once impressed to your performance, otherwise, you request for certificate and apply to other company.

Good luck!

apologize i'm not expert on this field

It is a fine balance indeed, but you can only get experience at work. Sometimes companies accept new graduates as a good future investment, but it is difficult to get a chance. Keep trying and hopefully you will get something.