building an app

I am developing my first app in flutter, I have developed almost 85% of the app, integrated with the firebase and everything setup from login page to main page, designed everything, provided access to the internal storage, able to access a particular folder fetch an item, BUT THE PROBLEM IS IM UNABLE TO FETCH THE GRID OF IMAGES CORRECTLY FROM THE ACCESSED PATH. AND ALSO WANT HELP IN THAT FETCHING IMAGES AND VIDEOS TO SHARE AND SAVE IN GALLARY.