You use column position 7 to indicate comments and page ejects. You must press the slash key twice because that key is used to access function key substitution keystrokes on keyboards that do not support function keys. You may be used to the word column referring to a column of text, as on a newspaper page. For our purposes however, a column is one horizontal space. For example, to get from column 8 to column 15, you would press the spacebar 7 times.
Line numbers are optional.
Note that when you begin typing in an editor session, you are in type over mode. This is the menu for loading and saving files and line manipulation. If the file is new, you will see your path and the extension . Your cursor will appear to the left of that extension. By default, the extension .cbl appears on the file prompt line.