I would like to create new links to my website, for the 1940's, 1950's, 1960's etc. How do I go about doing this.

Do you mean you want to create custom pages, where you include your own content about the 40s, 50s, and 60s?

If so, do this:

1) Click Edit Site Pages.
2) Activate any of your 8 Customizable Links by clicking the checkbox.
3) Click the Edit button next to the page to enter edit mode.
4) At the top of your page, name your page whatever you'd like.
5) Create your content inside of the editor window.
6) Press Save.