When I logged on to blogger today, I saw a notification regarding this designer and I immediately tried it. Since, I only have a free template for my contest blog, I tried the designer on that template. You can find the template designer tab when you click "design" on your dashboard and then on the page element page.
After clicking the template designer you will be redirected to the main designer where in you can choose what template you like. You can also change the background, layout, and color setting. You can also choose what layout and how many columns you like. You can even adjust the column widths as you wish.
You can also choose what layout and how many columns you like. You can even adjust the column widths as you wish.
I just did minor changes on my contest blog. I made two columns footer and I adjusted the column widths. When I have enough time, I will try to do more editing. Since, I am not that good in customizing blog template this template designer is really helpful.