amiga.lib contains all of the bindings to the system libraries. In order to create an Amiga executable you will need to convert amiga.lib to amiga.a to work with GCC.
If you find this all confusing I would suggest you download
VBCC instead of GCC. It only supports C but not C++ but so far neither does the Amiga APIs. It comes with some of the include files you'll need for programming and it comes with fd2pragma and instructions.
If you must download GCC there is an installer file on
kefren.be but unless you have already downloaded the 3.9 NDK it will be useless to you as Amiga.com has been redesigned and the 3.9 NDK is no longer available for download.
