How do files get into the External Dependencies in Visual Studio C++?

To resolve external dependencies within project. below things are important..
1. The compiler should know that where are header '.h' files located in workspace.
2. The linker able to find all specified  all '.lib' files & there names for current project.

So, Developer has to specify external dependencies for Project as below..

1. Select Project in Solution explorer.

2 . Project Properties -> Configuration Properties -> C/C++ -> General
specify all header files in "Additional Include Directories".

3.  Project Properties -> Configuration Properties -> Linker -> General
specify relative path for all lib files in "Additional Library Directories".

The External Dependencies folder is populated by IntelliSense: the contents of the folder do not affect the build at all (you can in fact disable the folder in the UI).

You need to actually include the header (using a #include directive) to use it. Depending on what that header is, you may also need to add its containing folder to the "Additional Include Directories" property and you may need to add additional libraries and library folders to the linker options; you can set all of these in the project properties (right click the project, select Properties). You should compare the properties with those of the project that does build to determine what you need to add.