Hi,
Put the company address in top right corner, followed by the date. use paper with the company letter-head.
5 July 2008
To Whom It May Concern,
The bearer, Mr. Fred Madawa, has served at this company, Silver Computers, in the capacity of IT Executive from . . .. to ... .
His service, technical and business skills, conduct and moral character have all been of the highest standard, and he has worked lhard and loyally for the company. I wish him well in all his future endeavours. Silver Computers would be more than happy to employ him again at any time in the future. \
If you require any additional information, I can be reached at (416) 555-3452.
Yours sincerely,
(signature)
Thomas Smith,
Manager, Silver Computers.