You're talking about source files (.dba files). To do this, open up the IDE, put whatever functions you want in there, and click the "save source" option from the file menu. Now open your main project, and use the include button in the program manager to browse to the source file. I recommend getting the Code Surge IDE, as the default IDE's include features can get a bit buggy, along with everything else with the default IDE for that matter.
Another point: People wont see your code, because when you compile your program, all of your code get's turned into machine code, and then into an executable. You never give out your actual code files (.dbpro, .dba), just the executable, and any media that the executable needs to run.
You can not make your own file type and have dbp read / compile it.
Please, read some beginner's tutorials on these topics (TDK has tonnes of them, click his signature link) and start learning this stuff on your own.
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And n00B, please, stop helping people. You dont know what the correct answer is, so when you "help", you're only making the user think they've figured it out, causing them to run into even more problems and ask even more questions, and then they may pass the wrong information on again.
