As Paul said it’s often easier to get a Solicitor or Gestoria to do the work, it won’t cost much and takes all the pain out of queuing and filling in all those forms if it’s your 1st year, after that you may want to try it yourself. For what you pay in fee’s with a Gestoria you will probably save in tax.
I knew one Gestoria who did this for 30 Euros a few years back.
Regards Ian