Add worksheets in Excel 2007

When you create a new workbook then by default three worksheets labeled Sheet1, Sheet2, and Sheet3 are created. You can add as many worksheets as you like. You can add worksheets at the end of the existing worksheets or before a particular worksheet.
To add a new worksheet at the end of the existing worksheets, click the Insert Worksheet button at the end of the sheet tabs.

To add a worksheet before a particular worksheet, you have to click on the worksheet tab that is to the right and then do the following. On the Home tab, in the Cells group click Insert and then click Insert Sheet.

For example, to add a worksheet between Sheet1 and Sheet2. Click to activate Sheet2, on the Home tab, in the Cells group click Insert and then click Insert Sheet. You will have the worksheets of the order Sheet1, Sheet4, Sheet2, Sheet3.
The keyboard shortcut is pressing Shift + F11.

You can also add multiple worksheets at the same time. Click the following link for information regarding this:
Add multiple worksheets at the same time