Coding Research/Create two page coding frame

Whats a good coding product for purchase to use to do a mobile app that works on apple and android? Whats a good program to use to do a mobile app that works on apple and android? Are there any coding websites where you can begin learning coding with a live teacher? Are there any popular web chat rooms that discuss coding? Are there any platforms or websites that sells a coding infrastructure for mobile apps? Are there any coding platforms that allow the user to download information and complete documents for a signature? Can this same platform allow the user to create accounts and make any necessary changes? Are there any coding experts available by telephone or social media? What are their names numbers etc? Create a coding page that allows you to upload forms that are connected to weblinks (pdf files) and enables the user to complete a form. The forms needs to be submitted back to the user account so it can be reviewed for processing and completion on the front end. An example of what i want is in the attachments.