First you have to be eligible as Phd Student at University of Montreal , so you need to apply directly using the online procedure that is in french so it's a little bit hard for people who don't speak the language , but you can easily translate using google. Pay attention to follow the procedure and send them all the material that they need. Then you need to apply fo the lab/department you want to work with. I applied at MILA by email sending my resumé, cover letter, research interests and the professors that I would like have as supervisors. Then if they are interested in you application they will call you to set an interview (mine was on skype)