To add a task input field and a button to allow users to add tasks to the todo list, follow these steps:
1. Add an HTML input field for task entry.
2. Create a C# event handler for the task addition.
3. Use data binding to associate the input field value with a C# variable.
4. Create a button with an event handler linked to the task addition logic.
Ensure to properly validate and handle user input to ensure data quality and prevent errors.