not completely sure i understand your question, but you could put in a
conditional format that basically says: "if this cell's value is more
that 250, turn red."

to do this, click the cell that you want to turn red.  Then on the
main menu, click FORMAT > CONDITIONAL FORMATTING...
Then set it to "Cell value is.....greater than....250".  Then click
the format button and on the patterns tab, click the red color.  clidk
OK..and OK

hope this helps,
dk