To start with your covering letter, have your name and address at the top right hand side, just like a formal letter. Split your covering letter into different paragraphs/sections starting with explaining why you are writing, followed by why the job is good for you, then why you are good for the job, to close it off, explain when you will be free for an interview and inform then of the earliest date you can start work (if the job description doesn’t already state this)