How to save files in this apps? Like i want to save my image so i can use it as part of my web design ?

Answer 1

HTML files (HTML in your android phone folders in File Manager) You can make a new file and add your HTML file there and so the picture you will need:
For example:

+CREATE FOLDER (HTML FILES)
+ADD FILES(Needed.png, Webdesign.html)
You just need to do like src="Needed.png"

You do not need to add a separate file for .js and css because you can directly inject them into HTML
JavaScript: <script> </script>
CSS: <style> </style>

Answer 2

how about html files? same as that i need a hmtl hosting site?

Answer 3

You can upload it to a image hosting site like postimg.org and use it from there.