Firstly, welcome to the forums.
While we are primarily here to help people with their Free Code Camp progress, we are open to people on other paths, too. Some of what you are asking is pretty trivial in the Free Code Camp context, so you might find that if you’re not getting the instruction and material you need in your current studies, the FCC curriculum will really help you get started. At a modest guess I’d say investing a 4-5 hours working through the curriculum here will really pay off. You can find the curriculum at https://www.freecodecamp.org/learn.
With your current questions, we don’t have enough context to know what you already know or don’t know, so it is impossible to guide you without just telling you the answer (which we won’t do).
It is pretty typical on here for people to share a codepen / repl.it / jsfiddle example of what they have tried so that anyone helping has more of an idea of what help is actually helpful.
Please provide some example of what you’ve tried and I’m sure you’ll get more help.
Happy coding 
im sorry i edited again so how to sort all even numbers in ascending order and then sort all odd numbers in descending order in javascript A = [30, 19, 9, 15, 55, 24, 3, 78, 46, 41].
you need to try to do something yourself, people are not going to give you the answer
You can have a look at the sort method and the remainder oprator. Here is the fCC challenge finding a remainder in javascript, and here is an example usage.
Also, where does the sorted numbers go?
A =[24, 30, 46, 78, 55, 41, 19, 15, 9, 3].
this must be the result
How is it possible to learn? can you help me please ? its my home task