For WordPress.com and WordPress.org
Widgets can add content and features to your sidebars. WordPress widgets are ready made widgets. There is more than one way to add a widget to your WordPress site.
1. Pasting code into a Text Arbitrary text of HTML widget.
Many applications such as Twitter will support widgets by providing a code to paste into a ready made “text/html” widget, creating this code is called creating a widget, for example Twitter generates a code when you create a widget, go to settings to locate the widgets tab.
WordPress.org: To place your Twitter Feed or GoodReads into a WordPress.org site paste the generated code into a text widget
Flickr Widget for WordPress.org: ID Getter
2. Collect your numeric user ID from the address bar in your browser.
Some specific application widgets you’ll need to collect your numeric user ID from the address bar in your browser. All you need is the numeric part, so copy the numbers and prepare to paste them into the WordPress.com widget.
Each application may have different instruction for locating this id.
GoodReads: To set up the widget, you need to sign up for a Goodreads account. Once you’ve created an account and signed in, go ahead and click on your avatar to see your profile page. The profile link will be near the top right of the Goodreads site:
GoodReads Widget instructions
Twitter Feed: To set up the widget go to the settings on your Twitter page to create a widget. Collect the your numeric ID from the url/address bar while editing your widget. All you need is the numeric part, so copy the numbers and prepare to paste them into the WordPress.com widget. Twitter Feed Instructions Here
WordPress.org vs WordPress.com
If you want a fully-featured site with your own domain name, unlimited storage for your videos and images, and no advertising, WordPress.com can become quite expensive. If cost is your most important consideration, then downloading WordPress from WordPress.org will be your most affordable option. WordPress.com is a commercial site where you can host your own site for free, but with some limitations.