The Lasso is hooping around your hand with your arm held straight above your head and the hoop spinning on a horizontal plain. You can practice this with your arm held out in front of you and the hoop spinning vertically around your hand first, then move onto the Lasso when you're feeling more confident. The aim is to have the hoop spinning as flat as possible above your head.
To come into Lasso start with the hoop in your right hand if you hoop to the left, and your left hand if you hoop to the right. Hold the hoop out in front of you and start to turn in the direction you hoop in, then slowly bring the hoop in towards your chest and up over your head. As you turn and bring the hoop above your head you want the hoop to roll across your thumb and into the palm of the hand. While doing the Lasso the hoop should remain between your thumb and your forefinger at all times!
Once you're confident doing this trick in one hand, practice it with the other hand, transferring the hoop from one hand to the other. You can also try turning while doing this move.
The Lasso is useful for more advanced tricks, such as the Corkscrew and the Vortex.