In order to do this just adjust the dates that Blogger has recorded.
Here are the instructions with some images.
- Open one of the pages or posts.
- When it is open on the right side you will see the date that it was published.
- Click on the words Published On.
- A window will open with a calendar which will allow you to change the date.
- You can change all of the dates so that they show up in the correct order.