Warcraft III is an highly advanced game.
You need some skills to make maps, to make maps, open up WE (World Editor)
Sorry but I cannot offer any further information as the World Editor is REALLY complicated for beginners.
You will learn, don't worry theres alot to learn, remember not everyone can make maps so you can just give it up hehe
Anyway since the WE is so advanced, there is no one tutorial to bring everything together as in the WE there are many things such as triggers, objects, terrain etc...
Good luck and remember play around with the WE to get used to it, then try the harder things to test yourself. Another thing is that a map shouldn't be hosted quickly on battle.net you will need test it too. So, you make a map, test it and think of it a idea.