Take your mother's vase. Set it on the end of that yellow line. Dock her into the hole around that vase, don't you mess it up. Do it in one move. =) Leave Ma's vase alone, forgetaboutit are you crazy? Grab a syrofoam cup or something, fillit with water. Dont you spill it while backing into the hole ...
Just roll down your windows, turn radio off and slowly back until you hear a crunch. Then pull forward and try again. Also try and pick a spot between 2 custom petes, those guys love working on their trucks.
Try this, Don't try to do a 90 . Get about 3 or 4 feet away. Imagine your in a clock. your driving straight at 9 o'clock. when your left shoulder gets to the other side of the lane you want to turn into count 2 or3 seconds crank hard right to 12 o'clock then hard left to 9 o'clock. Do a GOAL you should pretty much be pointing towards the hole. I also had a problem backing. A really good instructor taught me this just last week. I'm still a little slow, But i haven't missed since he showed me this. Good luck driver, remember GOAL and ignore those who criticize. Even the best miss once and a while.
It will click one day. Avoid blind side backing. I can do it but why do it if I don't have to? Remember it's not driving school. You can do an offset back if you want... or just put the ### of the trailer in the hole and pull forward and straighten out then you just have a straight back. Just get it in there without tearing stuff up however works for you.