You can use any slideshow plugin, but Weaver has its own that is well integrated with the theme.
GO to the plugin page > Add New, search for the Weaver Show Slider plugin.
Regarding Sidebar, you have two things to do. Choose a Sidebar Layout for your page, then place content in the Sidebar Widget Areas.
You can select Sidebar Layouts two ways:
a- Globally for each page type in Main Options > Sidebar & Layout Page
b- Locally, in each page editing page, you can select a different layout using the Sidebar Layout drop down list option.
As far as putting content in your sidebars, you do that by dropping widget in the sidebar Widget Areas (primary and or secondary) found in Appearance > Widgets.
You should take the time to read the help to learn more about this too 🙂