I've have started the free trial and added my titles, they are now in my list.. but how do I actually order them, I can't find any other links for this or help on their site which explains this. I'm sure there must be loads of ppl using the service, can any vets help me out? 
Just complete your list (i think you need 20/30 at least or they will send you emails saying that nothing is available on your list can you please add some more) and they will select what is available in the order you have prioritised them and send out what they have. THey email you when they send them out.