[senit] Chromakey - Blue screen

I am interested in getting a chromakey - blue screen set up - what resources
will I need ?

We have - imac with imovie, i can animate , new video camera, tripod.

We do not have blue screen, support for blue screen, additional lights.

Is there anything else that I would need ? e.g additional software, light
meter ?

I would like the set up to be portable so can take it to an off-site drama
group - particularly I would like to know how many (and what type) lights I
would need.

Thanks in advance, Alison