If the workflow process diagram that you’re trying to create is fairly straightforward and basic, try using Excel’s predesigned SmartArt charts as a foundation for your diagram. You can access this feature by going to the Insert tab on Excel’s ribbon and clicking on SmartArt. (Click any image in this article for a larger view.)

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From here, you can scroll through all the available SmartArt graphics in Excel. If you want to get more information about one of the objects, click on the item and a preview of that graphic along with a short explanation of its use will be shown on the right-hand side of the window.

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In addition to the SmartArt graphics that come preloaded with Excel, you can download several other designs at Microsoft Office Online.
As an example for now, I’ll select the Labeled Hierarchy chart found in the Hierarchy grouping.

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Once you’ve inserted the chart, you can make any modifications to the text simply by clicking on the placeholders and replacing the information with your own text. You can format this text in the same way you would any other text in Excel 2007. However, if you want to make changes to the appearance or shape of the text boxes themselves, you’ll need to go to the Design and Format tabs found under SmartArt Tools on the Excel Ribbon.

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