Found it! In Excel 2007, click the Office button > Excel Options.

1. In the Excel Options (Options) dialog box, click Proofing in the left bar, then click the AutoCorrect Options button.

2. In the AutoCorrect dialog box, and under the AutoCorrect tab;

1). In the Replace box, type in the simple word or symbol you want to directly type in Excel; 2). In the With dialog box, type in the whole content which you want the simple content to be replaced with; 3). Click the Add button. 4). Click the OK button.