I think lazyfoo's tutorials are simpler and you learn how different parts of SDL works. sdltutorials.com also shows how you can structure your code so I guess you can more other things from it but it can be a bit more unnecessary complicated if all you want is a quick examples of how it works.
I learned from lazyfoo so that's the one I recommend, but sdltutorials.com has a nice forum though.
Most people just learn from what's available online.
I often find the SDL documentation to be useful to look things up http://www.libsdl.org/cgi/docwiki.cgi/SDL_API
Looking directly in the SDL source code can also answer many questions that you can't find answers to but maybe it's not to be recommend to a beginner.