如何通过VBA基于其他单元格值更改单元格的背景颜色

I have two columns A and B in an excel sheet. A column is the drop down list that contains "Yes" and "No". And I would like to change the color of B cell that base on text value of A cell from drop down list. For example, if I select "Yes" in A1 cell than the B1 cell should show Green color. A2, A3... etc.I have two columns A and B in an excel sheet. A