This page also allows you to upload your resume (bottom right corner) so long as it is an Adobe PDF or Microsoft Word (DOCX) format. Learn how to write effective resumes and cover letters, view sample resumes and cover letters, and get tips for completing job applications.Browse Indeed's library of free cover letter examples, templates and advice. Learn how to write a cover letter for a job with tips from career experts. Browse professional examples to impress hiring managers. The purpose of a cover letter is to introduce you and briefly summarize your professional background. On average, it should be around 250 to 400 words long.