Photoshop Cs3/ How do you Convert an image into a Brush?

I dont know what i did but i was messing around and i turned one of my images into a brush so now i can select it and resize it and all that stuff as a brush, it seems preety kool but i couldnt find any videos on youtube explaining how 2 do it..

So does anyone on here know what 2 do to turn the image into a brush?
If so can you give me some step-by-step procedures Thanks.

How do I get a brush into PhotoShop?

I downloaded some brushes for Adobe PhotoShop. I just want to know how to get them into PhotoShop!!! I’m a whiz at the computer, but this I don’t know!!!

BTW, I want a step-by-step process. Don’t say stupid stuff like “How should I know?,” “Computer Nerd,” “I don’t know,” etc.!