How to Respond to an email from a HR Representative?

I am currently looking to respond to an email but I am not sure how should I adress it? I was referred by an employee to apply for a position , and now he is asking me to sent my resume back to the HR person whom he has included in the email? It is important for me to write something concise, polite and professional please help. My response should include a thank note and, the indication that i am sending the resume attached.