Back in the 80s, there would be no help sheet for a game like this (excluding some of Infocoms larger games). The idea is that you just try loads of different actions until something happens.
Ok so... after bit of fiddling I've deduced that the basic movement is 'GO <direction>' and also 'Leave' so I'm guessing 'Enter' works as well. Frustratingly, the delete/backspace key doesn't work in the Emulator.
But the first command is quite brilliantly, 'GET LAMP'[1].
The game itself is very 'Hobbit' in style with the drawing of the locations.
https://archive.org/details/zx_Secret_of_St._Brides_The_1985...
I cannot find the bit that tells me what the commands are.... Been a while since I played a game like this