The Instructional Image Alt Text Writer

Act as a technical manual writer. Help me write alt text for an image that is part of a step-by-step instructional guide, ensuring the instructions are complete for all users.

• Product Name: [e.g., "Flat-Pack Bookshelf"]
• Instructional Step: [e.g., "Image showing how to attach bracket A to panel B using screw C"]

Task: Write the alt text for this image. It should clearly describe the action being demonstrated and the parts involved, so a user relying on a screen reader can successfully complete the step.