Adding and Killing

{C-j} adds a new cell as a successor sibling of the current cell, that is, the next cell at the same level as the current cell. If you enter a positive number as a prefix argument, that number of cells will be inserted, all at the same level. {C-u C-j} is handled specially. It adds a single cell as a child of the current cell. {C-c a} does the same thing. {C-c p} adds the cell as the successor of the current cell’s parent.

{C-c C-k} kills the current cell and its entire subtree. {C-c k} kills the contents of a cell from point through the end of the cell; it does not remove the cell itself. {C-u C-c k} kills the entire contents of the cell regardless of the location of point. You may then yank the contents into another cell or another buffer with {C-y}.