To use User Meta login form as widget, go to: Appearance>>Widgets.
At the bottom of that page you will find a login widget option named User Meta Login. Click User Meta Login and choose where you want to put the login form as a widget from several options. After selecting one, click Add Widget.
An extra field will be added then in Content Sidebar named User Meta Login. Configure this widget field according to your need. Put a Guest Title of that widget which will be seen only by guests or leave blank if you want it without any title. Do the same thing for Logged-In User Title which will be seen only by logged-in users. Check Hide this widget when viewing login page not to show this widget in Login Page.
When you have done, click Save.
Then browse your site and you will find a login widget there.