How To Learn
Open up your scratch program, if you havn't installed or downloaded Scratch go to scratch.mit.edu, and look for the big download button. Once you have installed scratch go to where you installed it, usually under C:program files:Scratch, open up the file and start scratch.
Now you may be a little "overwhelmed" and unsure of what to do, what should i press, what am i even doing, why is there a cat? All of these questions will be answered and more, you'll soon be a master at Scratch and be able to make any thing you can imagine.
Creating A Sprite
First thing your games going to need is a sprite, prss the button at the very bottom of the stage window, the one that looks like a paint brush assaulting a folder, you'll then be taken to a window where you'll asked to draw or paint a sprite. Let you imagination go wild, create whatever you see fit to, and make sure it looks good :D
Creating A Background
Once you've clicked ok and imported your sprite into the stage then your almost ready to start programming.... BUt before that you want a background right, somewhere your character can live, somewhere he can fight monsters, or we'll.. anything. Once again you'll be greeted with a wonderful paint menu to design your background... do it. Also right click on the cat sprites picture on the bottom of the stage, and click delete.