Adding widgets to the main static page

I’m very new to wordpress.

I’ve added a widget to “Main Sidebar” but it’s only appearing in the blog, not anywhere else. How do I add widgets to sidebars on the main static page?

http://spacechronology.com/sc2/

Basically, how do I add anything to the space to the right and left from the main page? Is it done strictly through widgets or is there an other, manual, perhaps, way of doing it too?

Thank you so much in advance. I have decided to transfer my website to WordPress and am still learning the nuts and bolts. Which brings me to a second question, should I expect any complications when I change the address of my new wordpress site from a secondary directory to the main one, overwriting my original site? Is there a way of preserving the links of pages, for instance wordpress has given a particular page the following address: “?page_id=6” can it be changed to 1940s.html? The alternative, I suppose, is to redirect the original 1940s.html to ?page_id=6, but it’s not as desirable.