The Context Diagram is commonly used in collecting the requirements tasks in project management, system analysis and business analysis, and for many researches. It depicts the relationship between an entity and its context and can help in making sure that we didn't miss any of the stakeholders and their requirements. Usually the context diagram will contain only one level of details. Here is an example context diagram for the "Laptops for schools" project described in my book:
The diagram included many important stakeholders like: Students and software vendors, however, I deliberate didn't include two of the important stakeholders that are usually included in such projects. Try to analyze who could be these stakeholders and update the diagram by adding them. Add any other stakeholders that you may find suitable to the diagram.