～たがっています is "want to (verb)" for the third person. Kare wa nihon ni ikitagatte imasu. --> He wants to go to Japan. Kare wa nihon ni ittagatte imasu. --> It doesn't exist. Kare wa nihon ni ikitagatte imashita. --> He wanted to go to Japan. Generally we use ～たいです(want to verb) for the first and second person and ～たがっています for the third person but there are cases in which we say ～たいです for the third person. I hope this was helpful and the professional teachers or other people explain more about it.