Welcome to CAD ZDRIVER.
You have to practice, and it's best to have someone spot you, until you develop some skills.
One thing that will help you, is if you have a sliding tandem, slide your tandems all the way back.
That slows the rate of swing, and puts your pivot point closer to your back doors.
If you loose sight of where you are, get out and look at how you are doing.
When I first started out, I was jumping out of the truck a lot to spot myself, especially at night,
and you'd see me in the back lot of a Truck Stop, out where I was all alone, practicing.
If you can, have someone help you in the beginning, to get you started.
They can help talk you through a few times, offer you some tips as they see how you do, and where you are having problems.
Most truckers will always be happy to spot for you, and many will even offer their help, without you asking sometimes.
It's going to cause you some nerves in the beginning.
We all go through it, so be easy on yourself, and don't worry about making a mistake, that is how you learn and by practice.
Don't let anyone back your truck for you, help you yes, but don't give up the command of your ship.