Load an image from www and save it for offline use

Hi,

I am having a really hard time finding a good scripting tutorial (not js language tutorial, but how to use js to create and manipulate stuff...). So I would appreciate if you guys could help me by posting the full js script for my problem or pointing me to a good tutorial about that :)

My Situation: I need to download an image from a URl. let's say www.my.url/image.png. I want to use this image as a texture for a box that will totally fill the screen (It's for android and ios). I need the screen to do not allow the rotation of the device screen and maintain the portrait format. This image needs to be stored locally on the device so the user does not have to download it everytime and can use it offline.

What I got so far: I read that you can use the www() to load the image, but that's how far i went. I did not find how to store the image as a texture, how to create a box with it as a texture (GUI or not), how to lock the screen for rotation, and I don't know how to save the image locally.

Thanks