How to manage multitask in iPhone

Question

When I click the home button on the device. This is a part of my delegate:

- (void)applicationWillResignActive:(UIApplication *)application
{
    NSLog(@"resign active");
    //[[NSThread mainThread] cancel];
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"enter background");
    //[[NSThread mainThread] cancel];
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    NSLog(@"enter foreground");
    //[[NSThread mainThread] cancel];
}
- (void)applicationWillTerminate:(UIApplication *)application
{
    NSLog(@"terminate");
    //[[NSThread mainThread] cancel];
}

I uses NSLog to understand which method are called when I click the Home Button. This is output in console.

2012-01-20 15:55:55.853 MyApp[5955:11f03] enter background
2012-01-20 15:55:55.855 MyApp[5955:11f03] terminate
Program ended with exit code: 0

So, when I click on app in background (clicking two time the home button), it launchs again showing the first image and then my first uiviewcontroller.

In which way I can resolve it, and resume app from uiviewcontroller that was on the top when user clicks home button?