Arcade game

Im creating an arcade game... im just not sure how to handle the collision detection. What I want to happen is when you shoot an object that is 20 pixels wide, 20 pixels high that it will perform some event. If you could help me and give me a brief description on how to use it. BTW Im using BITBLT

-BFF

there are a dosen threads about this already, for example this one (it was right under/above your post)
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