Everytime i want to create an ebook, in my mind I was always afraid of work hijacked by others, and hurt sales.
what should I do so I can focus on making ebook without fear?
Well, if you release your book, you might lose a few sales to piracy. But if you don't release it, you definitely won't have any sales.
If you look through the questions on here from people who are stupid enough to ask where they can find pirate ebooks, most of them want the latest bestseller or something they were supposed to read for their English class. Nobody wants to get the less popular stuff for free.
As a new author, your biggest problem is obscurity, not piracy. What you should be worrying about is not that people will want to read your book for free, but that they won't want to read it at all. There were 350,000 books published in the US alone last year. How are you going to be noticed among all that noise?
Most people are honest, and accept that if a book is worth reading, it's worth paying for. But they have a limited amount of money and patience. You should assume that anyone who wants a pirate copy of your book will be able to find one in a matter of minutes. Your job then is to avoid doing anything that will cause them to go looking for it. That means writing a good book and selling it for a fair price, and making it available in as many countries as possible, from as many retailers as possible, in as many formats as possible. That removes any excuses the reader might have about "I'd buy it if I could." Anyone who still pirates after that probably wouldn't buy your book even if you made it impossible to pirate, so it's not worth chasing them for money.