To render an image of you're 3D file, point the camera at your 3D model, then on the top of the page where it says 'Render', click that then choose 'Render Image' from the drop down image. When Blender finishes rendering press F3 and save the image. This creates a .png image of your 3D model. You can press Esc to get out of the render window or to cancel rendering.
Making a .GIF is a little more involved, first you have to render out all the frames of your animation into your project folder. In the render settings under output (located in your properties panel), click the file icon next to the '/tmp\' then choose the file directory where you want it to put the frame images, next be sure you have set your start and end frame, then on the top of the page click 'Render' then 'Render Animation' (or press Ctrl F12), when it finishes you should have a set of images in the directory you specified. Now all you have to do is turn these images into a .GIF, I use Beneton Movie GIF for this, it's a fairly easy program to use, just open the frame images up in Benton Movie GIF (you can hold down on shift or ctrl to open multiple images at once), change the settings to your liking and save.
I am using Blender 2.6 right now if you are using an earlier version, it may be a little different.
I hope this helps, feel free to ask questions anytime, I'll be glad to help out the best I can.
Hmm, if you used 'Render Animation' or Ctrl+F12 try looking in your c:/tmp folder (this is were Blender places the frames by default).
If you rendered a single frame (F12 or 'Render Image'), you have to press F3 to save it.
Yeah, I worked out of that folder for awhile before I figured out how to change where the stuff goes XD.
Blender may write over those files next time you render something of the same format though, so if you are going to work from the tmp folder, be sure to copy/paste the files where you want them before rendering anything else.
To change where Blender saves the frames, click the button below the red arrow shown below, you will have to do this with every new blender file, and be sure to change it after each new render unless you want it to overwrite the last files.