Next, after the style sheet is opened for editing, you can make changes to the cells just as you would make changes to a cell in a regular notebook. For the style sheets included with Mathematica, the cells are grouped together based on functionality (e.g.Plain, headings, input, formulas, and headers). These cell groups must be opened to see the style definition cells. Each style definition cell is marked with the text "Prototype for style". For example, the cell defining the Text style looks like this in the default style sheet.
Prototype for style: "Text": Text
After you select a cell, you can use menu commands or the Option Inspector to apply options to the cell. For example, to change the font for the cell:
1. Click the cell bracket. The cell is highlighted. 2. In the Format menu, choose the desired font from the Font submenu.
The text in the cell is now written using the new font.
Other options not available from the menus can be set via the Option Inspector. Further documentation is available on the Option Inspector.