To active your WordPress Widget in WordPress admin area:
Go to Appearance > Widgets menu.
Choose a Widget and drag it to the sidebar where you wish it to appear. There might be more than one sidebar option, so begin with the first one. Once in place, WordPress automatically updates the Theme.
Preview the site. You should find that the “default” sidebar elements are now gone and only the new addition is visible.
Return to the Widgets Panel to continue adding Widgets.
To arrange the Widgets within the sidebar or Widget area, click and drag it into place.
To customize the Widget features, click the down arrow in the upper right corner to expand the Widget’s interface.
To save the Widget’s customization, click Save.
To remove the Widget, click Remove or Delete.
If you change WordPress Themes, the Widgets will return to the left side of the page in the Widget Archives or Available Widgets list. You may need to add them again and rearrangement depending upon the Theme’s ability to preserve other Theme’s Widgets.