Intonation isn't nearly as important in English as in Chinese. In Chinese you need to use tones to speak the language, whereas in English correct intonation just make you a better public speaker. English speakers rarely consciously control their intonation, and their intonation largely depends on what mood they're in. Usually only people like actors, presenters and politicians consciously control their intonation. All you have to do is vary the pitch of your words just randomly enough that you're not speaking in a monotone or in any pattern that is obvious. If try to do that consciously, your English will sound much more presentable than most natives speakers. Just don't vary your intonation so drastically that you sound like a robot. Here's another tip: try to end the last syllable of each sentence with a fourth tone if you want to sound confident, and use a second tone if you want to sound uncertain or inquisitive.

You could search youtube for "How to speak English with an American accent" or "How to speak English naturally." I would also recommend watching television and movies in English.