Hello Atish,
If you have properly configured the one-page template, your right sidebar will only appear on the blog posts page for on secondary pages.
The one-page template we designed has many sidebars areas to place widgets.
I would suggest you start by going to Appearance > Setup Parallel and follow the steps there.
Then go to the Parallel Options dashboard to begin customizing the site.
Let me know if this didn’t help you.