Johnny Walk is the name of the NPC that will give you "daily" quests to receive an Old Bag reward. When you open the old bag (open it on the class combo you want the elite skill for), it will automatically give you the next elite skill certificate that you qualify for. You then turn it into another NPC that is right inside the gates of Heffner Camp in the cul-de-sac area to the left. I don't recall his or her name, but he or she should have a title referring to skills or trainer or something.
There are NPCs in just about every major area of Coast of Opportunity and Xaviera that give you old bags. You don't have to do the ones from Johnny Walk. However, they are the easiest, IMO. But the xp/tp will obviously scale depending on which area you're in, so if that's a concern for you - go straight to Inferno Garden in Xaviera!
