how to write a business letter and hoew I improve my writing skills

Kindly go through the Study Material on 'letter writing' provided on the website. The 'Writing Section' of your Study Material will provide you with a detailed discussion on how to write essays, speech, articles, debates, etc. Once you have gone though the samples, we would request you to frame answers on your own. You will be able to improve your writing skills only through constant practice. 

All the best!