Add most basic useage of libreoffice_calc.

source/2/2.2/2.2.2/libreoffice_calc.rst

@@ -3,6 +3,10 @@ Chapter 2.2.2 Libreoffice Calc
 
 Libreoffice Calc is a spreadsheat program included by default in Lubuntu.
 
+Useage
+------
+To move between cells press the arrow keys. To enter data into cells type in the keyboard. To sum data from cells in the cell where you want the sum is to press the button that looks like Σ character and then drag the mouse over the cells you want to add.  
+
 Version
 -------
 Lubuntu ships with version  6.1.1.2 of libreoffice Calc.