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Start by creating a sketch on the XYPlane. Under Tree Outline, select XYPlane, then click on Sketching right before Details View. This will bring up the Sketching Toolboxes.
Click on the +Z axis on the bottom right corner of the Graphics window to have a normal look of the XY Plane.
In the Sketching toolboxes, select Rectangle. Create a rough Rectangle from starting from the origin in the positive XY direction (Make sure that you see a letter P at the origin before you start dragging the rectangle. The letter P at the origin means the geometry is constrained at the origin.)
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