Help With A Westie??

hi,
my mother got a white westie from the dog pound the other day, as far as we know she in 3 and neutered. my mother has a jack russell who she has had for 9 years this dog is trained completely. now when the westie goes to toilet she is doing it all over the back garden (the other dog goes out into the field) is there a way to get her to use one place or go into the field? also today she went out and rolled in all the sh**, my poor mother has just puked her ring up from the state of the dog?
any suggestins please….no smart comments i not in mood for them