Android Programming, help using the life cycle properly?

Hello world, I am creating an android application. Before I want to upload my application to the market, I want to figure out how to leave my entire application without only clicking the home button on the phone, but the return button as well. Ohkay, hopefully I can explain this well enough... pardon for my horrible grammar which I have to work on badly.
HERE I GO:
I created a menu where the user see's a variety of categories and has the option to go into the specific categories by clicking the desired topic/button. When the user clicks the desired category they enter a new activity. Of course if the user wants to go back to the menu activity to enter another activity all they would have to simply do is click the 'return' button on there phone, you know the one with the swirly arrow? Anyways, I created a home button for that on the application so they can choose either or for heading back to the menu screen. When the user leaves the 'categorized activity' it gets finished because I used

onpause()

function using the word

finish();

The only activity that should be alive is the menu screen. The only flickering I see is when I press the 'return touch' on the phone in the menu screen activity other then if I pressed the 'home touch' on the phone the application exits fine. I want to stop the flickering in the main menu activity so if the user pressed the 'return touch' there will not be any flickering. The code I used for the main menu activity is:

@Override
protected void onresume() {
        // TODO Auto-generated method stub
	super.onresume();
}

I am basically trying to set the main menu screen where the user has the option to use the home or return touch to exit the app. But I do not want this to interfere with the category activities because those only appear when the user wants to see the a specific category, then it gets finished once the use either returns to the main menu or just exits the whole thing. I am still a noob learning to cut me some slack.