Excel's basic building blocks are its worksheet pages, which are simply tables, or grids, you use for storing information you want to manipulate—usually in calculations. For this reason, you'll want to learn as much as you can about entering data into a worksheet.
To enter some bit of information into a cell—which is really just a text box—simply click the cell using the mouse and begin typing. When you press Enter or click the Formula bar's Enter button, Excel places whatever you type into the cell. (If you don’t see the Enter, Cancel, and Edit Formula buttons, click the Formula bar to display them. They are also displayed after you enter something in a cell.)