Click "Edit this group" (This option is at the right side of the page)
Select the layout, for example Vertical, Horizontal or 2 column layout, select other information, for example Group name, status, profile image etc and click on "Save" button.
Now click on "Other" button in your group section. Click the "HTML" and then click on "Edit" and copy the code.
Go to your WordPress Blog.
Navigate to "Appearance>Widget" and drag the "Text" widget from the "Available Widget" section to your blog "Sidebar".
Paste the code you just copied in step 6 in the "Text" widget.
Now visit your blog and the group widget will appear in your blog sidebar.