Thank you for the reply!
I figure it out now. What happen is, when I tapped F2 twice then go to manage app the click HelloWorld. The text won't load. So, I try another way which to click F2 the click the square icon(or it's a group of square arrange to form square-like shape ) then pop the apps menu along with the Helloworld which i clicked and display the app. I don't have a android phone yet so I don't know how to navi in the emulator. And, the logcat confuse me a bit since it gave the same error even the app loaded nicely. here my error message:
08-17 13:54:24.164: ERROR/HelloWorld_logger(408): Hello Activity: startingto.Android.HelloWorldActivity@40645ea0