Because the textures of wolves are overriden in the mod it will mean when you come across an ordinary wolf in-game it will have the same black textures as dragons. Wolves still look like wolves except that they are now black.
To go there you will first need an Eye of Ender which can be obtained by killing Endermen. Tap on the ground to throw the Eye of Ender and follow the direction it goes until it only leads you to one area.
Dig down there and you should find an End Portal room. Place an Eye of Ender in each of the End Portal blocks (12 in total) and the portal will appear.
You will now be teleported to The End. Up in the sky a big, black dragon will fly. Surrounding the place are several black pillars with some sort of flaming creature on top. The dragon will regenerate health from these pillars so before trying to kill the actual dragon try to destroy all the flaming creatures first.