Hi there,
The sidebar won’t display on Sela’s home page by design.
Instead, the image in the top section of the home page should expand the full width of the screen. The reason for the white space on the right of your home page is that that image is currently only 890px in width.
Sela works best with featured images on the home page that are at least 1180px wide.
If you have specific widgets that you’d like to display on the home page, then you could add them to the footer area. If the same widgets are also in the sidebar for others pages of your site, you could use the widget visibility settings (this feature comes with Jetpack) so that they only display in the footer of your home page.
Let me know if that’s clear or if you have any extra questions.