How to use the Nikon 50mm f/1.8 D lens?

Just purchased a dslr and received a Nikon 50mm f/1.8 D lens as a gift. So I'm pretty new with the lens. Just wanna know does the f-stop works only on f22? I tried the others which goes to f1.8 but it wouldn't lock and I couldn't take pictures. So how do you use the other f-stops?

Added (1). I'm fully aware of the aperture and shutter speed setting in my camera. As well as the A mode and S mode.i've been using a dslr for 3-4 years. The thing that I don't understand is the 50mm lens that i've never used before. It has a dial to change the f-stops ON the lens. And only f22 can be locked (red lock button on the lens). If i change the value of the fstop, let's say f2.8, it can't be locked. I tried putting it on A mode but it doesn't seem to work. Only f22 can be used and not the others. What i'm doing now is putting f22 on the lens dial and changing the aperture setting in my camera. It seem to work nicely. But i was just wondering what are the use of the other f-stops ON the lens if it can't be locked like the f22 on it? Why can't the other values be locked?

Here: http://thegreatdeals.org/index.php?k=Nikon+50mm+f%2F1.8+D&c=all

You lock the aperture ring on the lens at the minimum aperture (f22) and control the actual aperture of the lens via the aperture control wheel on the camera body.

This is a manual focus lens on camera bodies that do not have a focus motor (D3000, D3100, D3200, D5000, D5100)

You have to change the shutter speed also.

If you are outside, and have your sensitivity set at ISO 100

Then proper exposure would be f/16 @ 100 (125) of a second.
You could set the camera to aperture priority. This is where you select the lens aperture f/1.8-to-f22
In aperture mode after you select the aperture the camera selects the shutter speed. However if the ISO is to low or too high you may have to adjust your ISO so you get a hand-holdable shutter speed.
This principal is the same for All lenses, I'm surprised you didn't run into this with the lens that came with the camera.

I realize that today's instruction books are written by I don't know who, but it seems that qualified tech writers have been replaced by the Chinese, who can barely speak English! I would recommend getting some of the books by Scot Kelby to help you build a foundation on which to take better pictures.

This lens is designed to accommodate older and newer cameras.

On older cameras, the aperture (f-stop) is adjusted by the ring on the lens.

Newer cameras, such as your DSLR, you control the aperture via camera body controls. Thus, to use this lens on your camera, you lock the aperture to f/22 (minimum aperture size) and the camera body controls the mechanics of the aperture. They have a lock on f/22 so you don't accidentally rotate the aperture ring which then messes up the ability for the camera body to control the aperture.