1. Select the blank cell where you want to draw a slash header, where we select the first blank cell. Go to the Design tab, and in the Table Styles option group, click the Borders button.
2. In the pop-up Borders and Shading dialog box, select the options in the lower-right corner of the dialog box preview, select the Cells option in the Drop-down box that applies to, and then click OK to exit the dialog box.
3. A slash has been added to the selected cell, and you can now enter text in the cell.
Method Two
1. Select the blank cells that you want to draw a slash header for. Go to the Layout tab and click the Draw Slash header button in the Table Options group.
2. In the "Insert Slash Header" dialog box that pops up, in the table header style Drop-down box, select a header style, enter the text you want in row heading and column headings, select the appropriate font size in the Drop-down box for font size, and then click OK.
3. You can see that the slash header and text have been added to the selected cells.