Select the cells you want to merge, including the cells that don't contain any data.
Click the Merge and Center button on the Formatting toolbar.
The cells in the group header are merged, and the data is centered. Repeat the steps in this task as needed to group additional columns in your worksheet.
INTRODUCTION
Using Excel's Merge and Center feature, you can group similar data under one heading. Columns of data usually have column headers, but they can also have group header information representing multiple columns.
TIP
Inserting a Row
If no blank row exists above the row of cells you want to merge and center, from step 1, click the row above which you want the new row to be placed, open the Insert menu, and select Row.
TIP
Undoing Merged and Centered Cells
Select the cells to separate. Next, open the Format menu, select Cells, click the Alignment tab, deselect the Merge Cells check box, and click OK.