Hi Narend ,
Use the MOD function.
Suppose your data starts from row 6 , and goes till row 77 , in column J.
Select this entire range from J6 through J77 ; in the CF formula dialog box enter :
=MOD(ROW()-ROW($J$6),8)=0
Select the colour of your choice , and press OK.
What this will do is colour the cells J6 , J14 , J22 , J30 , J38 ,... ; in every cell where the row number less the row number of J6 is an exact multiple of 8 , that cell will be coloured.
Narayan