I had wanted to change to three columns template but most of the templates I found were for wordpress. Finally I found a bunch here. One of the advantages about the templates provided in this site is that they are the upgrade version of the existing blogger two columns template. For example, my two columns template in green has been upgraded to the 3 columns template, still in green.
Unfortunately, these templates are not perfect and they do have many bugs. Before converting, it is wise to save a hard copy of the existing source code. I have spent hours to find out how to put back my background image as it disappeared after the conversion and it didn't appear when I switched back to the two columns one. Someone raised this issue by commenting on the site but later this person found the answer himself. Apparently you have to go to delete the header element and recreate it. To delete the header element you need to go to the HTML of the template and replace the locked='true' to 'false' in the div tag for the header. Remove the header completely then recreate it. The background image was still off and I had to readjust the photo size to make it fit.
Anyway, if you guys have problems viewing / commenting or it takes too long to load compared to last time, please let me know.