Dear Karl,Re:xxxxx------------------------------------------

i'm hard这句有点不知所云.另外,语气有点生硬,不大像求职.我给你修改了一下,供你参考.
Dear Sir/Madam:（最好不要直呼求职人的姓名）
Please allow me to apply for the position of data entry assistant which you advertised on Internet.Now I am still a student.I am good at communicating with others and have a strong sense of responsibility.I am skillful at listening,speaking and writing in English,which are required in the position.If you are interested in my application,please give me an opportunity.
Sincerely yours
xxxx
另外,你的求职信过于简单了.你可以再加些内容,例如年龄,性别,就读院校之类的.写的越详细,你的成功几率越大.建议你以后将这类问题发到英语区,会有更多这方面的人关注你的问题.最后,祝你面试成功!：）