I simply picked from a list of contacts listed that would be interested in providing students with summer internships, I read a little bit about the background of each contact, whether they had hosted other student interns in the past, and then prepared a CV and emailed the contact I thought would most likely hire me along with a description of who I was. The contact emailed me back right away and we set up a time to interview at their office. They told me it was to discuss my interests and experience relevant to the internship.