You only need to position the wire in between the jaws and close. The spherical jaw will press the wire in the concave resulting in a nice 50 percent circle loop. Concave pliers can also be great for wire wrapping jewellery craft. You could begin to see the spring mechanism https://spoilmevintage.co.za/2024/11/20/chain-nose-pliers-uses-unlocking-creative-diy-project-ideas/