How to take composition photos on a Nikon D3000?

I have to take three pictures, and two of them being rule of thirds and deading lines. I can't find my manual for my camera so I need to ask here.

What settings would you use for compostion pictures, and also how do I get rule of thirds and deading lines?

Also what is composition exactly? I mean what kind of pictures would you take for it?

Ok, I've stopped laughing now!

THat won't be in your camera manual - that will tell you how to operate the camera, not how to compose a shot.

Composition is how you arrange the subject of your photo to give a pleasing balance.

Oh boy. Somebody is a little confused. Composition is the placement of your subject(s) in the frame of your viewfinder and is not changed by any settings. For rule of thirds, imagine splitting the image in your viewfinder into a 3 by 3 grid with lines. Your subject should be placed along one of the outside vertical lines, preferably where it meets with a horizontal line. I didn't explain that too well, so here's an example:

I'm not sure what you mean by deading lines. If it's a typo, and you mean leading lines, those are lines that draw your eye to the subject of the photo. Example here:
The lines in the field draw your eye toward the windmill.

Composition is not a setting on your camera. It is the art of leading the viewer through your image and presenting what you want the viewer to see. You do that by thinking about the subject and its placement and relationship to the other things in the photo. Here is a link for beginning photographic composition:

http://asp.photo.free.fr/Composition/photoProgramCompClass01.shtml

Go past the first few pages to the guidelines.

Oh dear. I think we need to start from the beginning because you sound well and truly confused.

Composition, is the skill of placing objects into a work of art. It is something which far predates photography, and much can be learnt from painters and photographers alike. So let's put the camera down for a while, and just look at some pictures, and get a feel for their composition. It's worth going to galleries such as the the Tate Britain where there are some classical works as well as some more avant garde pieces.

You'll find that if you slap something in the centre it does tend to dominate the image, and isolates that thing from the rest of the scene. By pushing an object away from the middle, it creates a sense of presence within the scene, of course take it too far and you risk marginalising that subject, although this may be what you are looking for. As a generalisation, this becomes the rule of thirds.

The tool you mention is the use of Leading lines (with an L), the purpose of this is to draw the viewers attention through a scene. You want to make use of lines which go from foreground through to the background.