The link below leads to a PDF file containing some lecture notes about celestial mechanics which I wrote for a mini-course given in Trieste, Italy in October 1994. They contain an overview of the basic facts about central configurations. The notes were hand-written and the file (which is just under 10 mb) contains a scan of the original notebooks.
Here are some more lecture notes (TeXed this time) on central configurations. These were for a mini-course given at the Centre de Recerca Matematica, Barcelona in January 2014.