Break one medium size coconut and scrape out the complete coconut. 

Add freshly scraped coconut and 1 cup of warm water in your blender and blitz it for few seconds. Strain it through a thin muslin cloth to extract the coconut milk. The first lot will be thick milk.

Now again add the scraped coconut with 1 cup warm water in your blender, blitz it and extract the second cup of coconut milk which will be thinner compared to the first cup of coconut milk.