First of all use the Left And Right Arrow Keys to set the direction for your grapple then hit the Up Arrow Key to throw and again quickly hit the Up Arrow Key to grasp the rocks.
Then you start to swing, and to increase the swing use the Left And Right Arrow Keys at the same time use the Up Arrow Key to climb up the rope.
When you feel that you have reached upto a platform then use the Down Arrow Key to land on to the platform.
Watch out for the rocks falling from the top. You can also save your progress by fixing a flag by pressing the Space Bar.