Doctor please can a man who is HIV positive get marriage with non infected woman or infected woman and give birth to a child who is HIV negative?

HIV . Yes. Absolutely. Even in nigeria the medical specialist know how to assist you in this situation. There are almost no babies being born any more with hiv. The male being on HIV medications and having the virus be suppressed fully will help you get to this miracle.
Yes. In a perfect world the HIV pos man will be on meds and undetectable. This will decrease transmission by upwards of 90%. The semen can be treated and washed (because its not the sperm that caries hiv.. It's the fluids along with it.). If mother is pos ( being on meds and undetectable is crucial). Caesarian at birth and IV HIV meds for the child have excellent results.