Just because you created a table with three columns doesn't mean that you have to be stuck with these three columns. If you decide you need a new column after your table has been created, you can add a column using one of the options in the Layout tab. Similarly, you can insert a row between existing rows, or even above existing rows.
The table that's been in the artwork for this course currently has three columns. But what if you want to add another column for last names, and insert a row for headings? Both are easy to do.
Whether you want to insert a column or insert a row, what you do starts the same way: select the row or column next to where you want the new item, click the Layout tab, and click one of the options from the Insert group. Then, look at your revised structure.