If you're asking for criticism, I can give you some feedback.
The resolution you're working at is too low. Simply working at your desktop resolution isn't enough to edit the details, so work a few times higher than your target size. The colors on Rin are also a little too high contrast compared to the rest of the artwork, and it looks a bit jarring. Rin and the bench are also full of white edges that don't look great.
The bench is pretty poorly cropped. The edges are either too soft and blurry because it looks like you used a soft eraser (green) or too hard because you didn't clean them up at all, and ended up with white edges (cyan). Rather than manually erasing hard edges, I'd select the bench (with a pen tool or something) and feathering in the selection before removing the background.
Rin herself is also poorly cropped (though idk if the bench is part of the same art as her). The dark blue bits are where the crop is most obvious. Her hair especially is where the low resolution fails you, as it's heavily aliased.
Looks like you missed a spot between her legs at the bottom (purple). Her shadows are also not quite right (also purple), and has white edges here and there.