i have been many people`s fan , but no one response me , which make me feel down
The short answer is that your English looks a little weak still to be honest. Don't worry though, everyone has to go through that at some point early on. This means that a native English speaker is either going to have to ignore a lot of mistakes unless it sounds really bad, or they'll have to stop the conversation often, which makes for veeery slow conversations.
So my advice has two parts. First, change your approach away from quotes like "I'm looking for someone to teach me English" to "I'm looking for native English speakers interested in learning Mandarin". Put some of your profile in well written Chinese too.
Then, after you've changed the way you market yourself, look for the most advanced (but not completely fluent) mandarin learners (who are of course native English speakers). Let them know that you both can speak mostly in Mandarin, but ask that they teach you some English phrases and help you when you do try to speak in English. Look at the process as a bunch of tiny experiments with the language you're trying to learn. Take small steps.
If you do this correctly over a long period of time you should gradually go from most of the average conversation in Chinese to most of it in English without hurting the flow of the conversations.
Why doesn't anybody help me with English?
I have followed many people's fan , but no one has responded to me, which makes me feel down.
Ok, a little honesty here: to date, you've been here two days and are following nine members. That's hardly anything.
If you want to be a little more "high profile" on italki, just be active! You've made a good start by posting in Discussions. Use the Notebook section to get corrections and feedback.
Help other people who are learning your language.
It's fine to contact members directly, but look for members who have similar interests to yours, or who you find interesting. When you write to them, say something more than "can you help me with English?" Start a conversation! :)
Please don't feel too down; its early days yet, and you'll get out what you put in.
By the way, your profile isn't as bad as some people when it comes to begging people to teach them English, but I would still make it more like "how can I help you learn Chinese". Yes, I know that that's not your ultimate goal, but you'll still learn English that way and it sends the message to others that talking to you won't just be a case of two people continuously hitting their heads against a wall.