Dear … (try to find out a named person)
State the job you are applying for and where you found out about it.
Introduce yourself and say a little about your skills and experience.
What do you know about the company and why do you want to work there?
Why you are interested in this type of work?
Research the company and their values, and relate them to your own.
Summarise your strengths and how they might be an advantage to the organisation.
Relate your skills to the competencies required in the job.
Thank them, and mention any dates that you won't be available for interview.
Put your covering letter as the body of your email, and add your CV as an attachment. You could save your CV as a PDF, as the formatting cannot be changed, and it will appear exactly as you want it to on the employer’s screen. Stick to simple text with short paragraphs and plenty of spacing.