Zooming into screen: just change the zoom of the page itself, like from 100% to 150%(pinch mousepad OUTSIDE DL box)
If you want to zoom in and out of your character, like zoom in closer to him/her, I have yet to find, if any, a shortkey. But what i do is either change the settings by clicking on menu>options>camera distance, or for my laptop I pinch the mouse pad out and in to zoom(just like using your phone or ipad to zoom) but your mouse curser must be in the DL box thing or else you'll just zoom the page itself and end up disconnecting. Course this only works if you are using a LAPTOP, not desktop.
Hope that wasnt too hard to understand lol