How to find information and help inside Emacs?
The first stop should be the Gnus manual (Say ‘C-h i d m Gnus RET’ to start the Gnus manual, then walk through the menus or do a full-text search with ‘s’). Then there are the general Emacs help commands starting with C-h, type ‘C-h ? ?’ to get a list of all available help commands and their meaning. Finally ‘M-x apropos-command’ lets you search through all available functions and ‘M-x apropos’ searches the bound variables.