Find the appropriate address for the organization(Walmart) . If feasible, find the name of someone to write, personal letters are much more effective than generic letters. You can often use news articles to find an appropriate person to contact. You may also call the firm and ask to speak to someone who is familiar with the part of the organization in which you are most interested. Then ask that person a few questions. Your cover letter can then thank the person for spending time with you before you ask for a job. Make sure you get the proper spelling of their name. You can also call HR and confirm the spelling and proper job title of the person you are writing.

briefly introduce yourself (max of two paragraphs, usually one). Use a professional format as specified in the text or as you can find online