Question About Adding Columns to WP with Coding

I had my layout made for me by someone else.

I have my current layout with my main page on the left side, and my 2 columns on the right side.

BUT I wish to have my new layout with my main page in the middle, and with 1 column on the right side and the other on the left (like the one I have for my old website here – https://steveaustinweb.blogspot.com).

How do I go about doing this?

You can e-mail me here if you need to – [email protected].

Thank you. Your help is VERY appreciated!!!