Reference+Material

http://www.techrepublic.com/blog/10things/10-cool-ways-to-use-excels-conditional-formatting-feature/3166

http://www.timeatlas.com/5_minute_tips/general/excel_autofilter_makes_spreadsheets_more_useful#.UJsDTGewV50

How to Use Summation Formulas in Microsoft Excel
 * Type an equals (=) sign into your spreadsheet cell, then alternate between clicking on the first number you need to add, then typing the plus (+) sign, then clicking on the second number you want to add, and so on**. Each time you click on another number, Excel will insert the cell reference for you (C4, for example), that tells Excel which spreadsheet cell contains the number (for C4, it's the cell in column C, in row 4). Your finished formula should look something like this:

=C4+C5+C6+C7