How do I brew Po Cha?

I have already arranged for the ingredients that I need to make one of the gems of the tibetan cuisine, the Po Cha. I have already arranged for the Sauce pan, six cups of water, two black tea bags, one tbsp of loose black tea, strainer, two tbsp of butter, one fourth of tsp of salt, half a cup of milk, but I don’t have a drink container with lid that is why I have arranged for a cocktail shaker. Now all I need is the procedure as I have lost the one I had borrowed from a colleague, so will you please tell me how do I brew Po Cha?