Change cell background color

[MarcoGT]

Hi all,

I have a FlexTable;
I want to set a default background color for cells (not all, I want to
exclude the first row and the first column; this should not be a
problem, I think I could use two for cycles and count rows and
columns); this color must change if some conditions are verified...

...what should I use?
addStyleName?
setStylePrimaryName?
setStyleName?

Thanks
Marco