To set up data validation:
- Select the cells you wish to affect.
- In the Data menu, click Validation.
- On the Settings tab, in the Allow box, click List.
- In the Source box, type the values, separated by commas, you want to allow.
- Click OK.
The Data Validation dialog box appears.
For example, try typing: blue, green, orange.
When you click on a cell, the drop-down arrow is available with the values you specified.
Note: In the Source box, you can use a formula or reference to a range of cells that contain your list values rather than explicitly typing those values in.
However, if you want to refer to a range of cells on a different worksheet in the same workbook, you need to define a named range, then refer to the named range in the Source box, =named_range.