He means make it look 3D. What a lot of signature people want to achieve is to make it seem like the render is standing in a sort of space and is interacting with all the effects around it. Without much tweaking, a render looks like a sticker overlapping a background, and that's when you come in and try to make it seem like it's all part of one image.
I think you've got this. The Gohan sig you're wearing is already taking this approach and looks great. You'll improve a lot more when you start taking requests and make new signatures every now and then. You're pretty good at this, so keep at it.