Tutorial 5: Styling objects
Look at your work so far—no literary minutia can escape your organizational prowess! Okay, so, the diagram makes sense, but it's not particularly attractive. Let's pretty up those objects with some style attributes.
You've seen the Diagram Layout inspector, but now we're going to start using the inspectors in earnest. They're convenient little windows full of controls that you can use to modify any object on the canvas, or the canvas itself. There are six Style inspectors, each one of which controls a certain element of the selected objects' appearance. The first inspector we'll use is the Fill inspector; if you don't see it on your screen, select Fill from the Style section of the Inspectors menu. Then, select Don John on the canvas.
Right now the selected object has a plain white fill color. Click the color well in the inspector's upper-right corner and then use the Colors panel that appears to choose a new fill color. If you like, you can even choose a blend style from the menu at the left of the inspector, then choose a different color for each well that appears. 
Next let's use the Lines and Shapes inspector to change the line drawn around the outside of the shape. There are six icons across the top of the Style inspectors window; click the second one to switch to the Lines and Shapes inspector. From there, try setting the stroke thickness to 2pt, and the corner radius to 5pt. This makes for a nice, heavy, rounded stroke around the shape. Choose a nice stroke color just like you did for the fill color. 
Switch to the Text inspector and click the Font button (the one with a big letter 'A'); this summons the standard Mac OS X font panel. Choose a nice font, then click the color well next to the Font button and choose a color to contrast the fill. Now you should have one quite charming shape object. 