Good afternoon Sir/ma,
I saw this opening at your office online and I am interested in this position.
I have good communication skills, I am good with computers as well as the Microsoft packages (Word, Excel and PowerPoint), I am a fast learner as well and I can work with people perfectly well. 
I believe I am good for this job because I have what it takes to perform really well if I am given the chance to.
I will be really glad to hear back from you, Thank you.