I have also followed a turorial that was set on normal maps. These are also refered too as bump maps as they show the detail of a high poly model but espically low poly. I found these maps difficult at first I as i didnt realise that all of the edge you wish to see must ethier be on an angle or at least champhered.
"render of the normal map I created on texture from the tutrorial"
"the normal map i created from a high poly model I quickly created"