How can I obtain a one-year visa to live in Thailand as a spouse of a Thai citizen?

You buy the 90 day Non-O visa based on marriage to a thai from the thai consulate in your country before you come here

Then you get 400k baht in a thai bank account in your name only for 2 months

and

when you have 30 days or less left on the 90 day entry stamp from the Non-O visa you go to apply for a yearly extension of stay based on marriage at your immigration office for 1900baht

These are the general requirements to get the year extension at the immigration office based on marriage to a thai. They are not office specific, check with your office once you are here for their hand out listing the requirements