It's understandably hard for people to grok, but if you don't think of jobs as a zero sum game (there are a limited number of jobs and if you get one, i don't) and instead think of them as producing economic activity (you are doing things that require resources and now have money that you will need to spend on services), it's easier to understand how more people means more jobs. Yglesias has made this point before but now he summarizes a study quantifying it, saying that every new immigrant adds 1.2 additional new jobs to the economy.