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It depends on how many colors of shading you're going to want. If it's 3 or less, you can use conditional formatting. If you've never used it before, have a look at the help file on it. If you're always going to be basing the colors off of I7, you can use the "Cell Value Is" condition, otherwise, you'll probably want "Formula Is." You can do some really neat things with conditional formatting.
If you still need help after that, post back with some more details like how many formats you need, and what the cutoffs are for each format (e.g. If less than 2, format green background, between 2 and 8, red background, etc.).
Hope that helps!