Here's all the information available (link below). Start by reading the "description" section. Also see the "Algorithms" sectoin.
You can read about any function by searching for it in the documentation (use the search field) or by using
doc smoothdata
If the documentation does not provide enough detail, fortunately the code in smoothdata is available to view. Open smoothdata and search for "if method == "gaussian"" for the gaussian method. It uses the undocumented function smoothgauss() which is also available to view. You could open smoothgauss(), put a breakpoint at the first line, then run your code. Once the execution reaches the breakpoint you can step through the code to see what it's doing.
