One of the most important things a new traveller to Asia has to consider is having a poo poo. This essential element of any holiday is so often ignored by the major travel writers.
This is a sad omission I will correct now.
The most awkward thing a new visitor has to contend with is the squat toilet.
As you can see from this example of a toilet in a petrol station, you dont sit down at all.
To use one, I find it best to completely remove your trousers and underwear before squatting down to 'work'.
New visitors to Asia often find a greater need for being close to a toilet after eating spicy food. Because you will have to remove your trousers, its better not to leave things until the last moment. The laundry services may not be keen on serving you if you leave things late.
These squat toilets sometimes have a hose to clean the clingy bits but most just have a container of water and a scoop. The idea is you splash water on your bum and use your left hand to scrape away any loose offerings. Many westerners find this a bit off putting so I usually suggest having a pack of soft table napkins with you at all times. These napkins are also handy when eating with your hands as the restaurants usually provide just a few very thin tissues but double up very nicely as wipes. (Wet them first to make things less like sand paper)
It is not advisable to use really rough, very cheap or thin ones.
Public toilets rarely have soap to wash your hands so its a good idea to have some in your day bag. I usually pinch the small ones from hotel bathrooms.
Almost all expensive hotels have sit down toilets but cheaper hotels and toilet umen (Public toilets) are squats. Newer shopping centers usually have some of both but older places, usually just squats.
The best and cleanest public toilets are in Pertamina petrol stations but many other ones are quite good. Unlike in Malaysia, I have yet to find a brown stuff encrusted, seriously disgusting one but there is time yet.
Finally its worth noting that, unlike in the west, many restaurants dont have toilets. If you think you may need an 'evacuation', best to go before you eat.
Its very common for western travellers to get themselves invited into homes out here especially if you wander away from tourist traps. A typical Indonesian home or cheap hotel bathroom will be equipped with a squat toilet and a large, square water holder. I have heard of westerners trying to take a bath inside the container. The idea is you use the scoop to pour cold water on yourself. Dont worry about getting the bathroom wet, its a wet room so no problem.
With that, I hope this will help you when you first come across an Asian toilet and bathroom.