Set Boundary for collision detection

gBallBaseLoc = (200, 300);
gGameRect = (0, 0, 300, 400);

the code above is said to set the boundary for the movie clip…
i tried it following a tutorial for collision detection but the boundary seems endless…meaning not working…
is there any other way to set the boundary ?
I’m need the steps…my actionscript is lousy…
Please please please help…:*(