To add and style your content in sidebars and footer you can use widgets, which you can set up under Appearance > Widgets.
There are default WordPress widgets that take the theme style though. More about WP widgets you can read here: https://codex.wordpress.org/WordPress_Widgets


https://codex.buddypress.org/themes/buddypress-widgets/



For example, in order to add the widget - find the needed widget, click on it and choose the area you want to place this widget.

