A cover letter should be written like a standard business letter: Address the editor formally by name, if known. Include your contact information, as well. This information is probably available through the journal’s online submission system, but it is proper to provide it in the cover letter, too. Begin your cover letter with a paragraph ...

First paragraph: include the title of your manuscript and the type of manuscript it is (e.g. review, research, case study). Then briefly explain the background to your study, the question you sought out to answer and why. Second paragraph: you should concisely explain what was done, the main findings and why they are significant.