Note the two hand positions:

1. The bar starts in front of the body. Grip with palms of the hands facing back and thumbs towards each other.
2. The bar starts behind the body. Grip the bar with palms of the hands forwards and thumbs on the outside of the bar. From the second position the range of motion is smaller. Try to raise the bar a little above shoulder level.

Perform 5 to 10 reps of each with minimal movement in the rest of your body. Arms should remain straight throughout. A wider grip makes the exercise easier and narrower makes it harder. Don’t force anything! Use a grip width that is moderately challenging. Over time you can narrow the grip.