Changing colors in table?

Okay..... Disclaimer: I am very much the newbie, so please bear with me. I have a piece of code that displays an array from a MySQL table. One field in the table is blank (and is displayed as an empty column of cells) at the moment. I want to have the blank cells display an image, value, or change its background color based on whether the numerical values in the previous 4 fields meet certain criteria or not. Make sense? Maybe? An example of what I want to show: If table 2 has a value that is less than 5, then the last cell displayed changes color to reflect that. If table 2 has a value that is between 5 and 10, then the last cell displayed changes color to reflect that as well. Please help if you can....many thanks in advance. (I can show my code thus far as well if that helps..) Thanks, Ryan