Rows

If you have an Excel table, you can easily add rows to that table. One way is to put the cursor in the bottom right cell of the table (but not in the total row if it exists) and then press the Tab key. A new row will appear. Below are two screen shots of the before and after. Notice that

After tapping the tab key a new row in the table is added. A new sheet row is not added. Notice that in column H the numbers remain the same.

A second way to add a row to the table is to use the menu system. Place your cursor where you want to insert the row in the table. Go to the Home tab (menu).

A third way to add a row is to select a row in the table, right-click and use the context-sensitive menu to insert a row above. Click on the screenshot below.

Columns

When you insert a new column, Excel will provide you with a column header automatically because all columns in a table must have headers.