Extended Web viewer Extension Link have same property -

When web viewer start loading if url does not contains your website home url then call activity launcher to open android default browser and open that url. Kindly tell me

use an if statement

Check out the Thunkable YouTube channel, there are lots of great videos for getting started:

A very good way to learn App Inventor is to read the free Inventor’s Manual here in the AI2 free online eBook http://www.appinventor.org/book2 … the links are at the bottom of the Web page. The book ‘teaches’ users how to program with AI2 blocks.
There is a free programming course here http://www.appinventor.org/content/CourseInABox/Intro and the aia files for the projects in the book are here: http://www.appinventor.org/bookFiles
How to do a lot of basic things with App Inventor are described here: http://www.appinventor.org/content/howDoYou/eventHandling .

Also do the tutorials http://appinventor.mit.edu/explore/ai2/tutorials.html to learn the basics of App Inventor, then try something and follow the Top 5 Tips: How to learn App Inventor