如何写好英文的求职信

Dear Sir,

I would like to apply for the position of secretary which you advertised in JobsPower.com. I have been handling most of the secretarial work at my present company for the past two years, and I feel that I can qualified to fill your position.
I am enclosing a brief resume as you requested. Please let me know if you want an interview.
One reason that I would like to be employed with your firm is that you are dealing with import and export trade. I would look forward to dealing with overseas companies and at the same time having a chance to use English more.