Glad you asked...
A letter of explanation should be well written. It has to be polite, not confusing and with the exact information and explanation. The explanation should be detailed and to show how the person really wants to make clear the things.
milena_st     How-To Expert
Then again, this answer might help you...
To write a letter of explanation, you need to be detailed and clear. Start with the date and your contact information. Next, write any contact information of the person receiving the letter. The body of the letter should include the subject of what is being explained, the explanation and why you are explaining. It should give all details in a way that is not confusing to anyone.
BobJHall     How-To Expert
About   .  Privacy   .  AskEraser   .  Settings   .     .  Careers   .  Ask Answers   .  iPhone   .  Help   © 2013 Ask.com