Download and run the latest binary release ( .exe file ) for windows from here.
Prove image magick is running by opening the command prompt ( Start button -> All Programes -> Accessories -> Command Prompt ) and type: convert -version
This should display the version of ImageMagick installed.
To use:
Open Command prompt ( as step 2 above ).
Using cd directory name get to the directory with the original image in - in my case I went
cd \ to take me back to the root
Then after the c:\ prompt
cd Documents and Settings\Barney\My Documents - This is where the image I want to modify is located.
( You can look at image properties by right clicking on it to find the path you need. )
I then ran convert test.jpg -resize 50x50 output.gif
I now have an image called output.gif in the My Documents folder.