What are you meant to include on them??

What are you asking?
Sending your resume out ? Cover letter? Click browse, attach to where it is on your computer.

Are you asking what goes into a cover letter? A brief detail description (short) telling a company or a specific human resource manager to an office what your typical day at work is, experience wise, or if its your first your ideal job; whether its an office job, a nurse, etc etc ... if you are applying for specific job title position, you say how you found it and where it was posted and sincerely thank the person in readding it...
if you need an example email me at mel.bouton@yahoo.com and i will give you one