This sample letter will help you understand how to write an invitation letter.

To
[Name of the Receiver]
[Street Address]
[City,State,Zip code]
Date MM/DD/YYY

Dear [Receiver]
I am glad to inform you on behalf [the name of your company], you have been selected for the post of [ the post which the receiver has been selected] in our company. I on behalf of our company would also like to congratulate you for the same.

So I on behalf of our company, hereby invite you to join us and make your future and our future better by playing your role at your best.
Clarifications or doubts if any, feel free to contact us.

With best wishes,
Sincerely,

[Your signature]
[Your name]
[Your designation]