If the reason the picture is not clear is due to poor focusing or camera
shake when you pressed the button to take a picture (the major reasons with
digital cameras) there is absolutely nothing you can do to it to make it
clear.
Automatic focusing with digital cameras is great, but
it does not work 100%.
Your picture may not be clear for other reasons. Plenty of photo editing
software to repair digital pictures (none can repair an out of focus
picture) to select.
Difficult to recommend any but you can look at the following software with a
Google search.
Microsoft Picture It version 9
Adobe Photoshop Elements 2.0
Adobe Photo Album
There is also a free, limited, but still quite good photo editor here:
http://www.irfanview.com/
If you have never edited a digital photo it may be a good software to start
with to orient you as what can be done with digital pictures.