Hi Johan,
Look at the previous posts. They really tell the story. It took me several tries but I finally got it right.
You need to make a set of icons - favicons - according to the requirements for mobile device. The program to do this is listed in the post.
Then follow the steps. The crucial thing is placing the tags in the NT web page. Again, the posts give the embed code and the location to put it in.
Move the icons, etc. to your server and it just runs. People can use the Hamburg menu on their cell phone to download it to their home screen. It places your icon on their device and links it to your program. It just works!
Apple would love you to put your app in their store - and they will happily take 30 % of all your revenue through the app.
I am not sure about Android.
I have not paid attention to the stores - I am not sure if the apps need to be native apps or not. Mine is NOT NATIVE mobile app. Mine is for a limited audience so I am not looking for world presence.
So, look back at the posts and if you have questions or get stuck, yell at us.
I hope folks who have insight about app stores will jump in as well.
Good luck,
Ron