Nikon D3000 Live View

So I know there's no live view on this camera and you have to look through the little square (not quite sure what it is called) So how do you know if you zoomed in or out enough? It's probably a very simple answer, but I just can't figure it out.

Looking through the viewfinder, you will see exactly how the image will be captured when you press the shutter release

That little square is called the viewfinder. It allows you to see through the lens of the camera. Basically, it's a bunch of mirrors so even if the camera is off it still works. As you look through it, turn the zoom ring on the lens. You should see the effect instantaneously.

Okay, hi.
That square that you are referring to is called the viewfinder.
You put your eyes directly on the rubber ring that surrounds it and you will see an image.
This image is reflected from your lens to a mirror and up to your eyes.
Whatever you see, is whatever you are going to capture. It is like live view, only better, because it is faster and more accurate.
When you zoom, zoom so that the picture in the viewfinder is exactly what you want to have in your picture.

But make sure you know that the image frame will be a bit bigger than what you see in the viewfinder, because your viewfinder has a view of 95%. Meaning what you see is 95% of the picture, the remaining 5 percent is a small border around the image, so make sure you take that into account when you take pictures.

Here's a little bit of reading, if you want:
http://www.luminous-landscape.com/tutorials/understanding-series/viewfinders.shtml

So who's the idiot who's giving negative ratings to keerok & fhotoace? They're spot on with their advice.

Look through the viewfinder, as good photographers have for years. Then zoom the lens and look at how that changes the image.

WYSIWYG is the rule. (What You See Is What You Get)
Zoom in- everything looks closer. Zoom out - everything looks further away.