see on your start menu program and find folder microsoft visual studio 6.0 tools on microsoft visual studio 6.0 menu. in this folder, running package & deployment wizard tool. you can make setup for your project with this tool. you just following every instruction and add file as u want.
But basically an Application Programming Interface (API) is a program written in C/C++ that you can reference in Visual Basic by translating the variables and including the libraries in a format that can be recognized in Visual Basic 6.0. The Software Development Kit (SDK) is now at Windows 2003 R2 and can be used in the VB6 environment.
Most of Windows is built on these APIs and when you wish to expand the capabilities of Visual Basic you can leverage the APIs in your application.
Check out the recently posted Sensing the Mouse's Movement Thread which I posted. It should be a good example of how to track the mouse position outside of a VB6 form using one of the SDK's APIs: GetCursorPos.
VB6 comes with an API Viewer with some prewritten or translated APIs for use in VB6: It has declarations (functions), Constants, and Types (structs in C) already translated and ready for use in VB6.