You can't produce fire because it's not possible without using matches and lighter fluid. This isn't Avatar and you can't shoot fireballs out of your hands. If that were the case half of the world population would be doing it, don't you think?
You can, however, work with the element for healing and divination purposes.
Our magical ancestors could easily preform what we today see as an advanced form of magic,they could easily manipulate the elements the 4 elements creating a fire ball will take you to doing quad-concentration cause you have to concentrate on the sphere that would be burning,on the fire it's temperature you'd have to make sure that the firball doesn't fly off somewhere and destroy something or that it doesn't backfire and actually kill you so it's best to try with simpler spells and when you are ready try a more advanced approach...
Fire balls CAN be created, but it requieres a lot of concentration and even more practice. I'm pretty sure you may find some info around the web. But don't forget fire is a force difficult to control and that you may lose control when asleep and end uo setting the room on fire. You'd better be very disciplined.