I believe you are working with a crosstab. Right click on your column label->format->border->color->background->x+2 and enter:
if currentfieldvalue = "Yourcolumnlabel" then crYellow else crNoColor
For the inner cells or totals, use a formula like:
if gridrowcolumnvalue("table.columnfield") = "Yourcolumnlabel" then crYellow else crNoColor
In the last formula, you would remove the curly brackets from the column field and replace them with ". If your column field is {Sales.Country}, then "Sales.Country" belongs in gridrowcolumnvalue(), while the name of the country would replace "Yourcolumnlabel".
-LB