Use Nikon DSLR to record directly into iMovie 2015

Hi - I want to connect my Nikon D3200 to my Macbook Pro in order to record directly into the most recent (2015) version of iMovie. Can someone please give me an ABC on thow to do this? When I connect the DSLR and choose Import, and then select the DSLR in the "camera" option I can't proceed to record - what am I doing wrong?