Pop up window is a window which is used to send the site visitors to other site automatically, when they come to your site.
Steps are given below :
1. Log in to your blogger account
3. Now a pop up window will appear.Then paste the below code in the content area
window.open('your url', 'poppage', 'toolbars=0, scrollbars=1, location=0, statusbars=0, menubars=0, resizable=1, width=650, height=650, left = 300, top = 50');
4. Now save the widget.
Customization :- Change the your url with the your URL.