Thanks Cassius. Dave yes, this is just a test, don’t worry!
Here are screenshots, can you point to what I need to do? First screen shot is of the footage, 
second one is of the matte I have made.

There’s another layer which is the image I want to project onto the folder, which isn’t visible in either.
As the board is coloured blue, I guess from what you say Cassius that it should be simple to mask it – but how to go about doing that seems to be too basic for all the tutorials I’ve looked at! Many apologies to make you go through such basic stuff, but it is massively appreciated.