Take 3 sheets of standard kitchen paper towel - preferably plain, white and fold in half on the diagonal so that they look like triangles.
Line the bottom of a large colander that you've either placed into the sink or in a large pan so that the sheets overlap each other with each point about a 1/2 inch to the right of the one below it.
Pour in the greek yoghurt into the middle.
Fold a 4th sheet of paper towel into 4 in a square/rectangular shape and place it on top of the yogurt and the fold the overlapping tops of the sheets into a package.
Put a plate that covers the surface of the package and then place a weight of some sort - I usually use a large can of whatever's on hand in the pantry.
Leave overnight in the sink or the baking pan to slowly drain.
The next morning, unwrap the package and place the labneh into a sealable bowl that you can refrigerate and take out what you need and serve with good olive oil. This is excellent on one slice of warm pitta bread with black and green olives (pitted, of course), drizzled with a little olive oil and rolled up. This is often breakfast or a snack back in Lebanon and is refered to as a "Sahnd-weesh".