I have read about Donchuang' and Iwould love to be there. What can you tell me about the place, how far is it from Kunming,

Dongchuan is about 250km from KM city.
From KM, you can go to the local North Bus Station to take a bus for Dongchuan District. Upon reaching there, you can hire a local car to reach see the Red Earth. The journey from KM to Dongchuan District costs about two hours and from Dongchuan District to the Red Earth costs about one hour and a half.

Thankyou for your answer, It was helpful
Do you think that I can arrange a taxi to Don chuang from my hotel in KM? How much should it cost?

It may not be that easy to arrange a taxi there. If you make it, they usually charge high. Well, I suggest you rent a car or minivan in KM to get there (you may also turn to your hotel for car rental). I heard the cost for a single trip shall be around CNY500, excluding the toll fee and fuel fee for your reference!