you need to go to the Ajuntament de tortosa, which is by the post office in the square near bar PICA PICA. you need escatura for proof of  address  and NIE. when you go in, there is a security man. tell him  departament de agricolas and he will give you a ticket,(just like the fish counter). you go through and take a seat, I didn't have to wait long. when you are called go to the counter and tell the person that you want fuego licencia por favor......and that's it. this is free. you will be given 2 sheets....1 for now till October 15th and another from then till march.... this is because there are different times
I hope this helps