Loop thru two ranges

Hi,

I'm trying to speed up my work in excel. I need to fill some cells in first range to get + values in 2nd range. Loop seems to be best way for it, but i'm not to good in VBA. In attached file you can find 3rd worksheet. Loop must go thru all cells in range B25:AN32 and change related cells in range B15:AN22 until cell value in bottom range will be > 0.

There is also 2nd problem I'd like to solve. In sheet KANBAN I've got simillar situation, but now i need to paste text into green range, to get values in bottom range until.

Both loops must run from top to bottom, column by column.

Thanks in advance for any help.