I dont know how to hold the lens properly if i want to adjust the focus, oh well im sure i will learn.
Lots of people seem to have problems with basic hand holding technique - but you've recognized the problem at once and it's longer lenses which tend to highlight the wrong technique so I'm glad you brought this up.
First things first - get your basic handholding technique right. This applies to pretty well any lens unless it's one meant to be on a tripod.
Stand upright. The right hand should be grasping the handgrip fairly loosely, the left hand should be cupped underneath the body of the lens. ( On shorter lenses like the 50mm etc, then the heel of your hand should be under the camera with the hand extending forward at a comfortable angle)
The left hand supports the full weight of the camera, but your elbows should be pulled firmly into your chest for added support. Your right hand is a far more relaxed grip and it enables you to concentrate on using that hand for smooth shutter operation.
With this basic position you'll find that with your left hand it's now a simple matter to operate the closer zoom collar with the thumb and second finger without moving your hand at all and without sacrificing any of your camera support technique. It's the quickest way to work and you're ready for that shot in an instant.
Similarly, with the manual focus collar, all that's usually needed is to slightly stretch the fingers forward, but operate the focus collar with the thumb and index finger. Try it - it becomes second nature after a while.
I see lots of people zooming and focusing by turning the left hand over with the fingers on top of the lens and the thumb underneath. This puts all the weight of the camera in the right hand, and is extremely stressful with a heavy zoom, apart from looking very amateurish.
You'll get used to the weight of this lens and the above technique will help a lot, but consider a monopod anyway - far lighter and easier to carry than a tripod.