I managed to do this! :D I am quite satisfied with the time.. Not with the wallpaper much. xD It took me several tries and even at the end it didn't work as I originally planned.
In this wallpaper, I used this scan and made a wallpaper out of it. I rendered the characters, used vector folliage and bird pack brushes and also used two textures (bokeh by lilapurple and Light texture by Kaneko yue) together with two gradients to make that background.

Dedicated to SakuraDust for winning at Name that anime world! Congrats and I hope that you are satisfied with your prize. :) I tried my best to make that scan into a wallpaper.

~ Thank you everyone for all your support and for viewing my work! ^_^