Add user menu with popup login form
- From WordPress Admin, click on Appearance -> Menus

 - Click on create a new menu

 - Enter menu name Account (you can use any name) and click on Create Menu button

 - Create Account menu and sub menu items with Login menu item and as well as other necessary menu items like below screenshot

 - Click on Screen Options from top right corner

 - Check on CSS Classes

 - Expand the My Account menu and under the CSS Classes (optional) add wt-account-menu
 - Expand the Login menu and under the CSS Classes (optional) add wt-open-login
 - Expand the Logout menu and under the CSS Classes (optional) add hide-for-guest
 - If you want to hide some menu items to guest (not logged in) user, add CSS Class to the menu item: hide-for-guest
 - If you need to hide some menu items to logged in users (show guest users only), add CSS Class to the menu item: show-for-guest
 - Click on Save Menu