redox titration

How do I calculate the moles of iron (ore sample)
and how do I calculate the mass percent of iron in the ore from this problem;

Ferrous ion reacts with permanganate ion Mno4 in acidic solution to produce the ferric ion fe3.  A6.893 gram sample of ore was mechanically crushed and then treated with Hcl which oxidized all the iron in the ore to the ferrous ion,next, the acid solution containing all the ferrous ions was titrated with .100M of KMno4 solution.  The end point was reached when 13.889 ml of potassium permanganate solution was used.

Help because I don't know where to begin