Take the gnomeregan quest from Ogrimmar. Once you take it, you will get another one to talk to some engineer in booty bay. Go to booty bay hand in the quest, the engineer will give you an item and the teleporter to Gnomeregan will be available to you whenever you have that item in your bags. TP to gnomeregan, walk from there to badlands. Quest in Orgrimmar is called Rigwars.
You can abandon the rigwars quest after doing the booty bay part.