Its pretty easy to make screen casts of software programs using a PC or a Mac. However its been difficult to take screen shots of an iTouch app. An easy way to do that is to press and hold the top button (Power) and the home button at the same time. If you hold it you should hear what sounds like a camera taking a picture (nice touch Apple) and the screen will flash. Your picture has been taken and saved to the photos app on the ITouch in the Saved photos folder.
To access your photos from a computer (PC). Connect your iTouch to the computer then click on my computer on your computer. You should see a icon for your iTouch. Open it and click on the storage icon to navigate to your pictures. My path looks like this: iTouch/internal storage/DCIM/100APPLE which opens my pictures. Your path may be slightly different as I have only tried this on my own iTouch.