The side that's up on your picture is the front of the slingshot. You can see that there’s a groove under the fork (the arms). You should grip the slingshot from the back (the side that is in contact with the hand in your picture), placing your thumb and index finger right under the fork. When wrapping around the slingshot, these will fall into the groove I mentioned above. Then, the other 3 fingers (middle, ring and pinkie) should wrap the lower portion of the handle, falling under the groove.
Basically, you should copy the grip in this picture, but with your slingshot the thumb and index finger wrap around the slingshot, rather than pushing against it. In this case, the pushing is done by the hand, the part between your fingers. You can see how the middle, ring and pinkie fingers wrap the handle, which is thinner at this lower portion of the handle.
This last picture can give you a better idea on how to grip the slingshot. Unfortunately, I don’t have one of these slingshots, so I can’t take a picture to show you the grip myself. I hope this helps.
The side that's up on your picture is the front of the slingshot. You can see that there’s a groove under the fork (the arms).
You should grip the slingshot from the back (the side that is in contact with the hand in your picture), placing your thumb and index finger right under the fork. When wrapping around the slingshot, these will fall into the groove I mentioned above.
Then, the other 3 fingers (middle, ring and pinkie) should wrap the lower portion of the handle, falling under the groove.
Basically, you should copy the grip in this picture, but with your slingshot the thumb and index finger wrap around the slingshot, rather than pushing against it. In this case, the pushing is done by the hand, the part between your fingers.
You can see how the middle, ring and pinkie fingers wrap the handle, which is thinner at this lower portion of the handle.
This last picture can give you a better idea on how to grip the slingshot.
Unfortunately, I don’t have one of these slingshots, so I can’t take a picture to show you the grip myself.
I hope this helps.