Right Column to display ONLY on main page??

I'd really appreciate any help you guys could give - I think what I am looking to do should be pretty straightforward. I have searched and read and tried things from various of the Zen tutorials but can't get anywhere - this is my first Zen Cart site.

I am making a web site for someone who wants the right hand column to display ONLY on the main welcome page so there will be plenty of room for products etc on the rest of the site. I assume that this could be achieved by turning off the right hand column on the admin settings and then over-riding that for just main_page in a tpl_main_page.php file but haven't a clue how to do that over-ride - I am completely new to PHP.

I have tried https://www.zen-cart.com/tutorials/index.php?article=233 but it only seems to give indications of what to do to turn one page OFF when the column is turned on in admin. I have tried reversing their instructions ($flag_disable_right = false;) but it seems it is not that simple.

Any help is much appreciated.