This varies with the theme that is active at the time, however the concept is similar across most themes.
The most common types of information you can adjust by using Widgets, is the sidebar, and footer of your website.
The Widgets page is separated into 3 main sections. Available Widgets, Active Widgets, and Inactive Widgets.
The Active Widgets section doesn't have a main title like the Available Widgets and Inactive Widgets section. Instead, this is an area on the right hand side, with multiple sections for different theme location areas.
Click on the Location Area name to show or hide the widgets that are currently active in that location.
While the Widgets are showing, click on the Widget title to show the settings for that particular widget.
You can rearrange the order of the widgets as they appear on the page, by clicking and dragging the widgets to the correct position. You can also move a widget from one area to another, rather than recreating the Widget in question.
Learn more about inactive widgets and available widgets.
