It looks like u forgot to erase over the render, take the top layer that is the bubbles and put it under your render,then set it to addition so it doesn't look like its just layed on there and work with the opacity. Ur render should be placed where ur Japanese lettering is or to the right a tad to be in the middle. Also u gotta add depth to the background by blurring and Gaussian blur with the two background colors. And lower the opacity on the black behind the lettering its a bit to strong I can see the square of black around it. And I always sharpen my render one last time so its not to dark, or work with the brightness/contrast. Hope this made since. Nice shot though, keep practiceing and you'll have it down in no time bro.