Teach yourself PHP
https://www.geeksforgeeks.org/php/
Developing custom sections in PHP
https://www.lianja.com/doc/index.php...ections_in_PHP
Developing custom gadgets in PHP
https://www.lianja.com/doc/index.php...Gadgets_in_PHP
Understanding UI layouts
https://www.lianja.com/doc/index.php...ing_UI_Layouts
Understanding Custom delegates
https://www.lianja.com/doc/index.php...stom_Delegates