Dear sir
This letter is in response to your job posting for an office assistant posted online. My strong written and verbal communication and interpersonal skills, coupled with my desire to work in a challenging and fast-paced environment make me a top contender for this position.

I offer great attention to detail, strong organization skills and excellent communication. I am excited about the opportunity to work with your company and hope to hear from you soon to set up an interview and discuss the position further. 

Thank you for your time and consideration.
Sincerely 
Precious Godspower