Good morning,
thanks for this awesome service.

I have the following requests/dubts:
-) How can I add pictures from my personal boxes?
-) There is any mobile app compatible with it to browse my collection?

Cheers,

All box art on each item in the database is added by Curators. They're heavily involved in getting things updated at the time they're added. Lots of times, Curators will go back and update with better pictures or more appropriate artwork. It's a constant work-in-progress type thing. We don't have anything right now that let's users add personal pictures to their collection entries.
Additionally, the site doesn't have a mobile app created but believe the site has been tailored to where it works, for the most part, on mobile devices. Not 100% perfect but hopefully will let you do the majority of what you want to do. I think Moho take feedback on that if there is something in particular you use that could be tweaked to show better on mobile devices.