Nikon D3100.how do I focus?

If it is a sunny day say at some falls and I'm taking pictures… Why do my pictures come blurry? Can someone give me some advice or a good link to aperture/shutter.etc because the manual didn't help!

Well I don't know your level of experience, so I don't wanna insult you buy asking you if your autofocus switch is on. On your lens, where it has a switch that goes back and forth that says A and M, make sure it's all the way at A for AUTOfocus. But if you're on autofocus, there's NO reason that it should be blurry…
Sorry, I'm not much help.

If you are using auto focus, Blake is correct about the A/M switch. I prefer manually focusing, as the camera does not always focus exactly like I want.

Also, without seeing an example of your blurry photo, it is hard to give advice. If the subject is moving, blurriness can be caused by too slow of a shutter speed. To stop motion using ambient light, you should try for a shutter speed of at least 1/250 (1/500+ is better) and that might mean raising the ISO or a larger aperture.

If your camera is anything like mine:
Rotate Mode Dial to S (for example). (shutter priority).
Turn Main Control dial to say 500 or higher. This is your shutter speed (1/500 of a second).
As was said, keep still and have your subject still.