edit php script that creates excel spreadsheet

I have a PHP script that exports data from a mysql data base and creats an excel spread sheet , formatted and creats seperate sheets for all my employees showing a wages breakdown . 1.I want to change how the script calculates a certain total. 2. add a new hard coded variable ( which is editable by me in the code ) 3. use hard coded variable to display 2 variable messages ( which is editable by me in the code ) 4. add in a field ( from the data base , which is already displayed on the sheet) to another set of cells. example the hard coded variable is £100 If a specific total is more than £100 display " you earned more than £100" if variable is les than £100 display this text " you earned less than £100" I will upload a sample ( not all of ) the code as it is now and also a layout of what I want done.