Adding or editing data for the X axis
Use the Category Groups field on the Data tab to specify values for the X axis. 
      - Next to the Category Groups field, click Add or Edit to open the Group Properties dialog.
 - Enter the name of the data you want to plot on the X axis.
 - 
            Specify this information: 
		  
            
- Label
 - Type a label for the X axis data or click the browse button to open the Enter Field/Expression dialog where you can select a label. This label is the legend that describes the data.
 - Group on
 - Click Add to open the Enter Field/Expression dialog where you can select the data field, shown on the X axis, for grouping the data plotted on the Y axis.
 
 - Click OK to save the changes.