Surely the course leaders should be supplying you with placements to apply for. Ask your personal tutor if they have any information on any companies available.

From my experience, I've found that applying for placements is the same as applying for any other job. I would write a CV and specialised covering letter and send them to the HR department of whoever you want to work for. Also some companies advertise placements on their websites, so look through those. Another option is to call the companies and ask to be directed to whoever is responsible for employing interns and express your interest in that way.

Hope this helps;