Good Resources
Control Sizes
The minimum recommended size of a tappable UI element is 44×44 pixels.
Background Color
[[self view] setBackgroundColor:[UIColor blueColor]];
Background Image
UIImageView *background = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"background.png"]];
[self.view addSubview:background];
[background release];
Positioning Views
This example moves a view down below the status bar:
[self view].frame = CGRectMake(0, 20, 320, 460);
Useful Code
How wide is the screen
float widthOfScreen = [[UIScreen mainScreen] bounds].size.width;