This sample letter given below will demonstrate how a charity letter should be written

To,
Name
Position
Name of the institution
Street address
City, State, Zip Code

Date MM/DD/YYY

Dear [The person the letter is written to]

The recent earthquake, as you know has caused heavy damage to life and property.To serve the needs of the survivours our social service organisation is collecting donations from a number of well established institutions. So it would be nice if you kindly make a generous donation which will help us in the relief work which we have undertaken to help the survivors.

Thanking You,

Sincerely,
[Signature]
[your name]
[your designation]