Are the poles sprung? Little bit of trial and error(abotu an hour or so) should do it.
Fitting them together to get he basic square shape - doe sit bend at the knees? - and the pulling the canvas over.
They really are simple to work out without instructions and so easy after you have done it once.
Congratulations btw on a lovely tent - was it the one that has just been on eBay?
This was my first pitching of our Montpelier
Similar to your Lichfield - this is it frame only and on it's knees ready for the canvas and then legs lifting
May give you sort of an idea (be prepared for a few 'words' if you aren't doing it alone!!!)
I start by laying the poles out on the grass (wherever I'm pitching)toget the basic idea of the shape right.