A journal can be a chronicle of your daily activities, a summary of your most intimate thoughts, or simply a way to keep yourself on track while you complete an assignment. To write a journal entry for yourself, consider writing about the events of your day, secrets you need to get off your chest, or random trains of thought. To write a journal entry for school, read the assignment carefully, reflect on what you've learned, and write your analysis of the information being reviewed. The exact rules of why, when, where and how you write are probably yours to determine in either case, but these points are usually good places to start.