There are no organized tours that visit the province of Ha Giang. If you want to get here, you will have to rent a four wheeled vehicle and find a local guide. You can ask your hotel in Hanoi, or go to some of the travel agencies in the French district in the capital of Vietnam.
To get here, I rented a jeep for eight days. You have the chance to rent a Russian jeep, which is cheaper, or a Japanese Jeep. I can only recommend the Japanese car. Some of the roads on this part of the country are in very bad conditions. Occasionally, roads may be closed due to landslides.