An excelent information found on the site BlenderNewbies.

Blender has a hotkeys reference that come in the package and can be found inside the interface.

 It's just click on menu Help > HotKey and MouseAction Reference.

The BlenderNewbies team made a tutorial showing how to use this resource.

Else, it's good remember thath in the Blender's instalation directory is included a .PDF with a summary of the commands, very useful to beginners.

The name of the file is BlenderQuickStart.pdf.