Before you start curling your hair, make sure that your hair is divided into two sections, with about three quarter your hair up and the rest loose and ready to tong.
You may want to use some heat protection spray on your hair here to protect it from the heat damage from the tongs.
Then start by taking sections of your hair, combing it, and then winding it round the tong, securing with the grip.
You might try changing the size of the sections to adjust how tight the curls end up being, and you could also try twisting the sections before putting them in the tongs.