1.  Select the cell for which you want to display a message.
2.  Click on the Data tab.
3.  Click Data Validation located in the Data Tools group.
4.  Select  the Input Message tab.
5.  Enter a Title in the Title field.  For example, Enter your name: 
6.  Enter the information you would like to have displayed for your input message.  In the example I
     might type: Please enter your first and last name.  Press Enter to start a new line
     in the message.  Text must be in the Input Message for the message to appear.  Make sure
     the Show Input Message when Cell is Selected check box is selected.