Only my main page is working - no secondary pages

I have established my market's main page with a few test product pages, widgets on the sidebar and menu at the top.

I can not seem to get anything to link to secondary pages I've written such as if I select a product from the home page, I can not see the full product listing/description. If I select an item from my sidebar, I am also redirected to an error page. Same with my menu items even though those pages are written.

I must be missing something? I'm not experienced with WordPress or site development, so please speak easy for me.

P.S. I am using Frame Market with the Market Press plugin.