Welcome on board
The document you need is the house registration certificate, called a tabi'en baan
ทะเบียนบ้าน
It"s usually done at the Amphur admisitrative office, but a larger tambon (sub-district) may sometimes also do this. It costs 25 baht.
Your wife, or anyone who has a house will be able to explain the procedure. It is not complicated.