The Table button [] lets you create a table. Please note that tables are for tabular data only and should never be used for content layout!
The most common misuse of tables is trying to use them to provide several lists side-by-side. This is a misuse because in a table there should always be a connection between all items in a row and all items in a column. When you use a table to put several lists side-by-side, you are implying connections between the lists that don't exist.
When creating a table, it must always have either a heading row or a heading column, if not both. When configuring your row and column count, keep in mind that any header row or column needs to be included in those counts.
Once you have placed a table, click on the first cell and start typing in information. Press the "Tab" key to move to the next cell or "Shift-Tab" to move to the previous cell.
If you need to modify the table structure, use the in-browser pop-up toolbar found directly below the table to make changes. It will appear whenever you have the editing cursor in one of the table's cells. The first button is for modifying a column, the second button for modifying a row, the third button for modifying the current cell, and the last button for enabling a table caption (which is highly recommended for accessiblity compliance.)
New rows are added automatically if you tab beyond the last cell. Through the pop-up toolbar you can add columns or rows anywhere (not just at the ends of the table), or adjust column, row, cell, or table properties.
A note on headings: You should never apply heading level formats to table headings! This is unnecessary and redundant, as the table structure will convey to users that those cells contain headings. Simply make sure that the heading column and/or row is marked accordingly. If you must, you can apply a font size increase using the Font Size drop-down, but this is discouraged in favor of keeping table formats standardized across the website.