Don't pronounce it like the English word "man". من (man) has a shorter vowel sound, the "a" sound doesn't last as long. Do not confuse this word with the word (min) in Arabic. (min) generally means "from", while (man) means "who". This word goes before someone's name, or a nominative preposition or a noun. It's function is exactly the same as "who" in question sentences.
Who is he?
Who is the manager?
Who are you?
Only when talking to one person.
من ذهب الى الـمدرسة؟
man dhahaba ila al_madrasah(-ti)?
Who went to school?
Who is a Muslim?