How do I draw my first walls and floor in a new Revit project?

Start a new project with the Architectural Template (File → New → Project, units in mm) and open Floor Plans → Level 1. Start the Wall tool (type WA), pick Basic Wall: Generic - 200mm in the Type Selector, set Height to Level 2 with Chain checked, and draw a closed rectangle by typing the lengths (8000, Enter, then 5000). For the floor: Architecture → Floor, use Boundary Line → Pick Walls, click the four walls, and hit the green check. Pick Walls is safer than sketching lines by hand — the floor keeps updating when the walls move. Answer "No" to the attach-walls prompt. Full steps: First walls and floor →