Grasp the basics (grammar etc.) before you start learning the advanced stuff. 学高级英语之前先把最基本的(语法等)学会再说. You cannot say "How to learn economic English?" that is not a question. "How to" can ONLY be used together in a title and DO NOT form a question: e.g. "how to drive a car" << a book maybe, teaching you how to drive. NB: not a question! In normal conversation we NEVER say "how to" or "when to" for that matter. Been in China for more than 3years and this is the biggest problem I see all the time. 问题是你是用中文语法去说英文: "怎么学..." 所以你很容易说错了. "怎么"多数不能翻译成how to! 比如说, "这个用英语怎么说?" 很中国人会说, "how to say this in English?" 这是错的! 应该是, "How do I say this in English?" 后者 "how do you say this in English?" 这样才对. 加油! 你还是重新开始, 复习你小时候学的英语, 会对你有不少的帮助!