If you know the cell address (P10 in this code) then you can do the following
in the click event for chkbox Ck1;
Private Sub Ck1_Click()
Range("P10").Select
With Selection.Interior
.ColorIndex = 36
.Pattern = xlSolid
End With
'Selection.Font.ColorIndex = 46
'Selection.FormulaR1C1 = "Test"
End Sub