To manage your widgets go to Appearance > Widgets. On the left you see the widgets and on the right you see the widget areas. Simply drag the widget you want to the chosen widget area then you can customize the setting of it. Finally click on Save.
Archives:
A monthly archive of your site’s Posts.
Calendar:
A calendar of your site’s Posts.
Categories:
A list or dropdown of categories.
Contact Info:
Display contact information fields.
Custom Menu:
Add a custom menu to your sidebar.
Links:
Your blogroll
Meta:
Login, RSS, & WordPress.org links.
Pages:
A list of your site’s Pages.
Recent Comments:
Your site’s most recent comments.
Recent Posts:
Display recent post with or without thumbnails.
RSS:
Entries from any RSS or Atom feed.
Search:
A search form for your site.
Separator:
Display line or space separator
Social Link:
Display social media links.
Tag Cloud:
A cloud of your most used tags.
Text:
Arbitrary text or HTML.