How to release shutter on nikon d3000?

I'm trying to figure out how to take a picture but failing.

Here, download the manual.
http://support.nikonusa.com/...534/sort/1, 2/r_id/116678
Look on page 53
Did you know to format the memory card before using it? Page 21
And how to hold the camera to reduce the change of image blur caused by camera movement during exposures.
Page 27

I'd advice you to return it and get a simple compact camera. It's impossible to use a camera in this class without reading some parts of the manual.

"Release shutter" essentially means "take a picture". The main button on the camera, near your index finger, is the 'shutter release' button.
Keep reading the manual, or consider taking a photography course.

You release it by letting it go.