Parted Magic can be found here. You will also need to use something like UNetbootin which will install Parted Magic onto a USB or CD. It can be found here.
Once you have Parted Magic installed onto some type of media device (USB / CD) reboot the system you are going to use it on and load from the media. (Either from a boot menu that will automatically pop up or you may have to go into the bios and set it to read USB or CD-ROM first on the next boot, it all depends on your motherboard. Usually pressing one of the following will get you into bios or a boot menu: F12 or Delete)
You should be prompted with a screen like this:
Press Enter or allow it to automatically boot.
Select “Partition Editor" as this is the application we will be using to resize our partition.
Now select the drive that you wish to resize.
Right click the partition you have selected and now click “Resize/Move"
Here is the basic layout of your partition that you selected. (Remember that it shows you the sizes of everything in Megabytes, not Gigabytes on this screen)
For our example we are going to change the 7.5 GB (7,679 MiB) partition down to 4 GB (4096 MiB). Once you enter the desired size press “TAB" as it will auto fill the free space. Now press “Resize/Move".
“Apply" the changes with the green arrow at the top of the application.
“Apply" again and now the wait begins!
If everything is successful you should have a similar screen to this! Click “Close"
As you can see our “/dev/sda" has now been resized from 7.5 GB (7,679 MiB) partition down to 4 GB. (4096 MiB)
That was it; all done!
Additional Parted Magic information can be found here
If you are interested in figuring out how to clone a partition to another hard drive check out my other guide here