how 2 write cover letter for applying exchange student

Probably your cover letter would first make clear what program you are interested in and how you found out about it.  That could be one paragraph.  A second paragraph could explain your experience and knowledge and why you think you would make a good representative for your university.  A third paragraph might be added indicating your enthusiasm for this program and your hope that you would have a chance to speak with your lecturer about your suitability.  Be sure to include your contact information so you can be reached by telephone or e-mail.

Good luck!