Your Scott, Foresman Handbook points out that writing about a process is a lot like creating a narrative. After all, in both, you describe a series of happenings, often in chronological order. However, as your handbook points out, in a process essay "instead of telling a story, you are explaining how something works" (40). The handbook goes on to explain it is important in process writing to list the important steps in their proper order.
Which steps are important enough to be listed in your essay? How much detail should be included as you discuss each step? Should the language be plain and unornamented or can it include metaphors and similes?
You can answer those questions only when you know your purpose in writing an essay.
Imagine, for instance the kind of essay you might write if you were explaining to someone HOW TO write an essay using a computer. You'd probably create a list of clear steps, speaking directly to your reader. You'd probably begin with a clear command--"Find and turn on the power switch"-- and end with the last step--"Log off by pressing the F5 button at the top of your keyboard." (By the way, in giving directions you'll usually use a direct or implied "you"--the so-called "second person point of view.")
Of course, if your readers are unlikely to know what a power switch and an F5 button are, you'll need to convey that information with words they can understand and perhaps with an illustration.
However, if your motive was not so much to create a set of directions as to lead your readers to understand HOW USING THE COMPUTER AFFECTS YOUR WRITING, you'd probably be less concerned about including all the steps you follow to write with your Gateway or Mac. Instead, you'd want to offer details that communicate your feelings about the process. You might even begin with a first person ("I") description: