what should i do

this is zsa zsa 2 years old.. i saw a korean lady with this poor dog . the dog is inside the box and has a chain on her neck .the chain is very rust and big for her neck. she is very dirty and smelly. she looks scared and hungry..i try to touch her she looks very scared. i feel sorry for her and thinking how come if a person who toke my Shia is doing a same to her that she suffering the way they care to the dog..i would be demonstated if i find out that my Shia is suffering..
i was looking at the poor dog then the ajjoma ask me if i want the dog. i said no . then she said you can have her for 50,000 WON
she selling the poor dog for 50,000 won to me ,she said she have already shots . i look at the dog she look scared and need to be loved
i pay her 50000 won to get a poor dog..i toke her to my home and give her a bath i find out that she have a few scars..i feed her she was very hungry and very unhealthy she look sick ..i massage her back and saying dont worry your safe now
i look at her eyes .. i think she have tears on her eyes..
after a couple days i found out that she is not poty train and poop every where even on a couch or bed..
thats the problem i have to clean the house..and i dont have enough time.
im thinking to take her back to ajjoma and not taking back the money ..
but evertime i look at her i cannot do it she looks happy now and gain weight..
i dont know what to do..she poop everywhere and she pee everywhere
shes 2 years old and i dont know how to train her..any suggestion ?