i like red hair but its rare, it  occurs naturally in 1–2% of the human population.
Why do they have red hair?
i have read that It occurs more frequently (2–6%) in people of northern or western European ancestry,
What other places apart from Europe?
well it can appear anywere, Just most commonly in people with two copies of a recessive allele on chromosome 16 
Can you explain better? Is it hereditary or it had to do with health issues?
it is hereditary just rare. Red hair varies in hues from a deep burgundy or bright coppe
Those terms seem to ambiguous, can you put it in a lay man's understanding?
well It is characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment . that is it pretty much
Do they have those with an artificial red hair,I mean the ones that are designed in factory?