How to write DWORD Value (32 Bits) within an existing Key?

I've been researching this over the Web and until I found it around here. The content on the web about this, from what I've seen is little too much. My question is as follows. How to write a DWORD value (32 bits) within an existing Key. Because I want to manipulate it within my project through a "CheckBox". Does anyone have a clue how to do this?