RE : "that how come a green material like grass clippings or stinging nettle that are generally wet can heat up a pile ?!! I thought browns what makes a pile heat, aren't greens juicy ?!
Sorry, you have it all backwards. Yes greens are juicy (as I said soft/wet). But GREENS are what heat up your pile through the nitrogen decomposition. Browns slow it down.
Here's a nice article about home composting http://urbanext.illinois.edu/compost/process.cfm It notes:
If the pile has more brown organic materials, it may take longer to compost. You can speed up the process by adding more green materials or a fertilizer with nitrogen (use one cup per 25 square feet).
When they say speed up as in finish faster, it also means heat up. But if you have plenty of GREENS, you shouldn't need to add fertilizer.
And re: "RainbowGardener, are you saying that leaves that the citrus tree drops are still considered as greens ?! Sorry I meant Loquat tree fallen leaves that have brownish color "
COLOR has nothing to do with whether something is a "brown" or a "green." Like I said before manure is a green. Whether your loquat leaves are brown or green depends partly on the process. Like I said, deciduous trees that drop their leaves in fall, reclaim the nitrogen and other nutrients before they let go of them, so what is left is mostly the carbon structure of the leaves. It is the same difference between hay (a "green") and straw (a "brown"). Both of them are stems of grain plants, it could be the same kind of plants. But hay is cut while the plant is still green and growing. Straw is cut after the plant is finished, when it has reclaimed the nutrients and dried out.
So what makes compost piles hotter is: oxygen (which is why we turn it, sounds like you are doing plenty of that), smaller particle size (which lets more surface be exposed to the oxygen, it's why you are chopping things, sounds like you are doing plenty of that), more "greens," and moisture.
We haven't talked about that. If you are in a warm dry climate, you may need to water your compost pile. I water mine, any time it is dry enough that I need to water the plants. The compost pile shouldn't be wet or soggy, but it should stay just damp, all the way through. If it completely dries out, it stops composting and just sits there. Not a disaster, as soon as the rain comes back it starts working again.
The other thing a compost pile needs are the micro-organisms that do the composting work. Someone mentioned compost starter earlier. That's what compost starter is. But the micro-organisms are present in any healthy soil that hasn't been treated with chemicals. So if you just scatter a handful of soil over the pile now and then when you are adding things, it may help. It doesn't take much, I really mean handfuls, not bucket fulls.
Re your parents: It is NOT a trash pile! Trash is what goes to landfill, mainly plastic. It is a compost pile, full of wonderful rich organic materials, that are going to turn in to a beautiful soil amendment. In my mind, that is the "magic" of compost -- all those kitchen scraps that might have gone down the garbage disposal turning themselves into rich black crumbly sweet smelling earth. Doesn't matter how fast or hot it works, it is still garden magic!