Select the cells you want to border
Go to the Home tab
Click the Borders drop-down in the Font group
Choose a border option from the list
For more border choices, click More Borders
In the Format Cells window, select the Border tab
Choose the line style and color
Click the border sides you want to apply
Click OK
Use the shortcut Alt + H + B to open the Borders menu on Windows
Use the Draw Border tool if you want to draw borders manually