As this is your first post I'm going to give you a fish. However, the purpose of this forum is to "assist" you write your own code. Not write it for you. Working with tables that have merged cells can be very difficult. By putting the cursor in the first cells (i.e., row five, column 8) this may work:
Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
Dim lngIndex As Long: lngIndex = 1
Do
If lngIndex = 4 Then lngIndex = 1
Select Case lngIndex
Case 1
Selection.Cells(1).Shading.BackgroundPatternColor = wdColorBlue
Case 2
Selection.Cells(1).Shading.BackgroundPatternColor = wdColorBrightGreen
Case 3
Selection.Cells(1).Shading.BackgroundPatternColor = wdColorLightYellow
End Select
lngIndex = lngIndex + 1
'Escape clause:
If Selection.Cells(1).Range.Rows(1).Range.End = Selection.Tables(1).Rows(Selection.Tables(1).Rows.Count).Range.End Then Exit Do
'Next row.
Selection.MoveRight Unit:=wdCell, Count:=Selection.Tables(1).Columns.Count
Loop
lbl_Exit:
Exit Sub
Err_Loop:
Resume lbl_Exit
End Sub