What can I add to this macro so that it only gets activated when the same
cells in column B have contents? i.e. B6, B8, B10?

Sub Target()
ActiveCell.FormulaR1C1 = "Target"
Range("C6").Select
ActiveCell.FormulaR1C1 = "Target"
Range("C8").Select
ActiveCell.FormulaR1C1 = "Target"
Range("C10").Select
ActiveCell.FormulaR1C1 = "Target"
Range("C12").Select
ActiveCell.FormulaR1C1 = "Target"
Range("C14").Select
End Sub