Yes, def use lights along the sides. The tissue paper should diffuse them. Although I made one and it didn't work (not sure what I did wrong, lol), that's the purpose of the tissue.
Others gave you good advice, check the white setting on your camera.
I use Photoshop but I do have Paint.net tho too
Here is what I would do in Paint.net
: if you go to adjustments>levels
and slide the input
it lightens the whole photo. then I slide the inner arrow
of the output
a bit and that darkened the colored part back up. Just play around with that and it'll come out pretty well I think
If you have any other questions feel free to ask, I'm happy to help if I can
This is what I came up with by using that method: Untitled.jpg