You want to make sure to brush between the braces and the gum. Angle the brush toward your gum and brush in small circles. Obviously, you want to brush all the surfaces, especially the chewing surfaces. For more specifics, please watch the video.
The most important thing aspect to keep in mind when brushing with braces is to spend enough time doing it, a minimum of 2 minutes two to three times a day. The most common area to miss with braces is up by the gumline.