Will not take picture

The D90, is a very good camera. I even know some professionals who do have one or more, to work with or have it as a backup for a bigger Nikon, because it will work with almost every Nikon lens. That means, it also works with the older AF lenses, that were made for analog (film) cameras.
To start, put the main dial on the top left, to the green camera (auto) logo or the one with the line through the flash logo, next to it. In both cases the camera works automatic , with a little difference. In auto it will pop up the speed light when there is little light, in the other it will raise the ISO and will not use the flash. without flash, if there is not enough light, the camera just won't make a picture.
when you are in one of the automatic settings, see in the view finder, where the camera will focus while you press the shutter half. It will place one ore more squares on one or several parts of your frame, where the camera "thinks" it should focus on. It this or these parts are the points you like to be in focus, then press the button full.

this should give better pictures. If it works, let me know.

I had a problem similar to this. Try taking off your glasses or removing your contacts and try again. Best of luck.

It need two AAA batteries to work. Insert that batteries and turn on the camera by pressing the push button on the top.It cant work without battery even if it connected to computer.
for taking picture,focus it on an objest using view finder and press the shutter butten.

Your camera is equipped with a optical diopter that will allow you to adjust the optics in the viewfinder to your eye. meaning bringing everything into focus as it should. The way I use this (set it) is to let the camera auto focus on a subject and then turn the diopter until I see the subject clearly.
It really helps if the subject is about 12 feet away (get it real sharp) and the camera is mounted on a tripod. Once set I put a little dot of paper white out on the diopter adjustment knob so if it gets turned I know and can quickly return it to the correct spot. I'm including a diagram where this adjustment knob is on your camera, have fun.

Diagram

Good day,

The problem you might be having is that the view finder is out of focus.
If this is the problem it is an easy fix.
You will see a small wheel next to the view finder (it has a + and a - next to it), look through the view finder and let the camera focus on an object. Now turn the wheel and you will see the image either get worse or start to come in focus. Adjust the wheel until you are satisfied with the clarity.

Please let me know if this was helpful!

Regards

Next to the viewfinder ther is a diopter adjustment so you can change the focus in the viewfinder. this is so if you need glasses the camera can be set for you. Start by focusing the camera on something, then slide to turn the diopter adjustment until it looks sharp and try not to bump it.

Digital cameras require lots of power. Bad electrical contacts can cause lots of problems so battery and camera contacts must be cleaned properly. Batteries may be fully charged, but will be viewed as low if contacts are not really good. The LCD screen is a low steady load, but when lens extension, optical zoom, focus, and flash charging are added in the capture mode; the load is very heavy. Bad contacts make cameras do strange things like making bad pictures or shutting off with the lens out.
Do not overcharge.
Reset by removing power up to one month is the ultimate non-physical repair for DVD recorders and other software using digital devices. Digital cameras reset to original settings if batteries are removed. Time required varies with function and camera, but try one minute. Check display and setup menu for non-auto functions and date/time. Remove extra memory to eliminate this as a possible problem. Insert fully charged batteries and restart the camera.

is there a little slider type bar/switch/button on the finder, most cameras have them to compensate for different peoples eyesight. if there is, look through it, put camera in auto focus and when its focused, look through finder and move bar/switch... til pic is clear

There was a recall on the N55 due to auto focus problems. You can do a google search or nikon.com email the support team and they will send you the paper. This is what I did, I wasn't charged since I had the correct papers. I, however, used one roll of film and my focus went out again! Mine doesn't even work on manual... If you want to try that maybe you will hae better luck than me. GOOD LUCK!

This is a defective CCD known to Canon. They will repair it free of charge. Go here for details: http://www.usa.canon.com/consumer/controller?act=PgComSmModDisplayAct&fcategoryid=223&modelid=8044&keycode=2112&id=29819