Place the muslin over a colander or sieve large enough to hold all the yogurt. Pour yogurt into the lined colander. You will notice a whitish liquid dripping out. This is called Whey.Bring up the sides of the cloth, and tie tightly with a string to form a sort of a bag. Tie the string around a wooden spoon and place it in a deep bowl in such a way that the spoon is resting across the bowl and the bottom of the bag does not touch the bowl. This leaves space for the whey to drip into the bowl.Place this apparatus in the refrigerator for 24 hours. Keep checking every few hours to remove any whey that may have collected. The idea is to ensure that the bag does not get submerged in the whey. Do not discard the whey, which is quite useful. For starters, it cane be used instead of water to knead dough.Once 24 hours are up, remove the bag and untie it. The yogurt should have thickened up considerably and should start to look like cream cheese. Transfer this to a bowl and add salt. Mix well.Take the same cloth and line a bowl with it. Transfer cream cheese to the lined bowl, and wrap with cloth on top to cover the cheese. Place a heavy weight on top of this. You could use a heavy plate, or another bowl filled with water. Leave this in the refrigerator for up to 2 days.After 2 days remove, unwrap and Voila, your cream cheese is ready!