Open the edit-rounded-rectangles.psd file in Photoshop. See the Layers panel on the right side of your workspace. If you don't see it, go to Window > Layers. In the Layers panel, click the "Background" layer.
Select the Rectangle Tool from the toolbar on the left side of your workspace. If you don't see the toolbar, go to Windows > Tools. Select white for the color fill from the Options at the top of your workspace. This specifies a white color fill for the rectangle. Select "No Color" for the stroke.
Notice that bright blue guides appear to help you position your rectangle. Place your cursor where the guides intersect at the top left corner. Click and drag from this corner to the bottom right corner, releasing your mouse to complete the rectangle.
Once you finish drawing your rectangle, notice that the Properties panel automatically opens. If you don't see it, go to Window > Properties. In the Properties panel, change the corner radius of your newly-drawn live rectangle. Enter "65 px" as the corner radius. The Properties panel applies the corner radius setting to all corners in your rectangle since the panel has linked corners (the chain icon) selected by default.
In the Properties panel, you can change the stroke and fill of your shape. Click the stroke color icon. In the color swatches panel that appears, select a light blue color to add a color stroke to the rectangle. Change the stroke width to "15 pt" to make the color stroke thicker.
To edit a rectangle that's already been drawn, you must first select it. Press "A" on your keyboard to select the Path Selection Tool, or click to select this tool from the toolbar. Click the "Rectangle - Location" layer so that you can activate that layer for editing.
Using the Path Selection Tool, click the light blue "Location" square. In the Properties panel, change the corner radius to "17 px" for all corners for this shape.
Select the other rectangles in the image to experiment with adjusting Live Shape properties. Try mixing and matching different corner radius values by clicking the link icon in the Properties panel. This allows you to toggle between editing each corner radius individually, or proportionally to each other.