"in the sidebar" is correct and it can be used in written English.
For example: "The instructions for navigating the website can be found in the sidebar."
The results of Netscape's beefed-up Search command are listed in the Sidebar, too.
We'll probably welcome refugees by putting the word Syrian in the sidebar of xHamster.
In the sidebar on the left you can add favourite contacts and folders.
The company website features a demonstration financial article that updates automatically each time you change a figure in the sidebar.
See the example in the sidebar.
Available reactions are listed in the sidebar (A).
The requirements report can be browsed using hyperlinks in the sidebar.
For 8 months these only appeared in the sidebar.
Instead, all of the info is now available right in the sidebar.
In the sidebar, among 'News Feed', 'Messages', 'Events' and 'Photos', there's a 'Questions' tab.
However, there in the sidebar was the Facebook logo, along with that of LinkedIn and Foursquare.
