penders - 6:35 pm on Oct 4, 2011 (gmt 0)

i tried setting a div tag of col4 and float left as i want it below column 1

If you want col4 below column 1, then that isn't a 4th column - that would be the 1st column of the 2nd row...?

If you currently have 3 columns, then presumably you have a width defined for col1, col2 and col3. Presumably the widths divide the content area into 3 (taking into account padding/margins)? In order to get 6 columns then you obviously need to reduce the widths of the other 3 columns so that the total width of all 6 columns is not greater than the total width of your content area. Or have I missed something?