Assuming your key cell is in column A, and your data begins in row 2, Select
your entire range (rows and columns) from cell A2 through M1000 (or
whatever), go to Conditional formatting, change the pull down box to Formula
is, and if it is just 'any' type of entry, type the following formula into
the box:
=$A2<>""
Then click on the format button and choose your formatting.
Let assume you want to color the range A:F whenever the rows A cell has data
Suppose you are starting with A1. Select the entire range, A1:F1000 for
example and choose Format, Conditional Formatting, pick Formula is from the
first drop down and enter the formula