Three are three parts in the picture. The part with the knurled ring is called a visual back. The ring screws over the threads on the back of the telescope, and provides a 1.25" tube for accessories to slide into. Currently inserted into it is a right-angle "star diagonal." It sends the view through a 90 degree turn so that when the telescope is pointed toward the sky, you don't have to get on your knees and crane your neck to look through it. The third piece is an eyepiece. It forms the image for your eye.
The magnification for this scope is calculated by dividing 2000 by the number on the eyepiece. That's 333X for this eyepiece. It's really for zooming in on a planet, once you've found it with a lower power eyepiece. The field of view with this combination will be just over a tenth of a degree. It's very difficult to find anything when looking at such a tiny part of the sky. As has been mentioned, you want a wider eyepiece (bigger number). You can get a 32mm Plossl eyepiece for a fairly low cost.
However, you could set the scope up with its base flat on a table and point it at some distant object (at least a mile away) on the ground, and you will still be able to scan around with this eyepiece. Once you have it pointing at something (which will probably be very blurry), there is a focus knob on the back of the telescope that you turn. It moves the mirror inside of the scope, so you won't see any changes outwardly, but the view should change. If it gets more blurry, turn the knob the other way. Keep turning until it comes to focus.
When viewing during the day, there will usually be heat waves that make it difficult to get really good focus. Pointing at distant streetlights at night, for example, you'll probably get better focus.
If the scope never does come to good focus, then it may need collimation, which involves adjusting the front mirror using the three screws that support it. Come back here for more advice before you attempt that.
When properly adjusted, these scopes can deliver amazing views.
Chip W