Simple question - Private String

Hi, I'm from Argentina,
I have this private string:

private string c_sRematePrivado = "<img src=\"/images/tabla/rematePrivado.gif\" width=\"17\" height=\"17\">";

Then I use it here:

cell = getCell(dr["denom"].ToString() + c_sRematePrivado);

And I want to make it visible /not visible using a local variable:

if (local variable)
{
    make c_sRematePrivado visible (can't use c_sRematePrivado.visible = true)
}
else
{
    make c_sRematePrivado not visible
}

How can I do it ??

Thanks !! ...