Set background Image for a Custom UIView

I am developing a paint application using OpenGL.

I am using "CUSTOM UIView" for drawing on a screen and another UIImageView to set background image to it. Have a look at screenshot to understand it clearly.. My problem is I am not able to set background image on either of the view.. I have to use different textures as a drawing board on which I have to Paint. Can anyone suggest what is incorrect in this approach??

I have used this code for custom UIView but not getting success.. but it shows white default background only..

- (id)initWithCoder:(NSCoder*)coder {
    UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"Rough_White_Paper_with_tape.png"]];
    self.backgroundColor = background;
    [background release];     
}