Is it possible to take silhouette photos like this using my Nikon CoolPix S 70? if so please let me know how? I tried but getting blurry images :(
You should be able to, but the controls (or lack thereof) on the s70 will make it a little difficult.
The key to getting a good silhouette is to put your subject in front of a bright background, then expose for the background.
The easiest way with your camera might be to set up your shot without the subject, half press the shutter, and then have your subject come to the right spot, and take the picture.
Also, remember not to use flash.
You'll also want to be sure you're using a tripod for these shots. You might not be able to get all of these with your camera (stopping action on a shot like this will be tough), but you should be able to get shots where the subject isn't moving quickly.
I was going to suggest the same thing as chills42, with you exposing correctly for the background and then moving the subject move in. Obviously this is less ideal if you're trying to shoot trees or a fence, for example, in silhouette, but maybe you could move the camera to get a clear view before you half-press the shutter?
The blurring you describe is probably down to the exposure not being fast enough, but as far as I'm aware you don't have control over this directly on your camera. I believe you can adjust the ISO when in Auto mode, though. Exposing for the bright background should reduce the exposure time a bit, but if this doesn't work you may have to use a tripod/rest the camera on something, or increase the ISO which will probably introduce more noise.