I guess there are no mining/blacksmithing trainers in Darnassus, as there are no mining nodes at all in Teldrassil. I recommend traveling to Stormwind City to train, as Elwynn forest has nodes aplenty. Remember to stick to mountains and hills when looking for your copper (and eventually, higher level nodes ;)).

By the way: You can download an add-on called Gatherer (there are others with a similar purpose, but Gatherer is my weapon of choice) to make your gathering easier, and look at http://mapwow.com/ for reference.

Good luck!

There aren't mining, engineering and blacksmithing trainers in Darnassus, but they do have them in Auberdine - next Nelf town.