Inventory manual or youtube instruction video

I notice that the official manual, nor youtube, nor anything else on the internet gives a CLEAR instruction how to do a network inventory by scanning the network, adding windows pc's, servers, with or without agent, giving a complete overview of all devices using different ways. This is realy a core functionality and a great puzzle to figure out. Although the manual states some technical features commands etc, it isn't clear about how to do the steps to configure GLPI to do this properly. It is driving me nuts and it is very sad that i can't find a good manual that is clea on this matter.... Please make some, or good instruction movies (ENGLISH screesnhots and instructions) and manuals.