Wants to Buy

You could start by consulting a mortgage broker to see how much of a mortgage loan you could qualify for, so you'll know if you can get a loan and how much you could borrow.
Then you contact the person or organization offering the house for sale, and you make a written offer for it.  Many real estate agents act as buyers' agents and one of them could help you with the procedure. or you could go directly to a real estate lawyer.  YOu'll want one anyhow, because if your landlord is facing bankruptcy, it's possible there are legal or financial claims against the house you should know about before you buy it.