( This question is from my dad ) right, He imagrated from Italy to England five years il y a and he didnt know that he had to register at the aire!!!

My dad imagrated from Italy the the UK five years il y a and he didnt know that he had to register at the aire! A friend of his told him that he had to register now, so he really doesnt know what to do, can toi please help :( I would really appreaciate it!!!!