Connect your two connectors. With the Route command, you'll wire matching pins on C1 and C2 together, route all of them, then exit routing.
On the left command bar, select Route to start wiring.
Click Pin 1 on connector C1.
Click Pin 1 on connector C2. The route is created between the two pins.
Repeat pin-to-pin to connect the rest — pin 2 to pin 2, and so on — until all pins are routed.
Press Esc to finish routing and return to the selection tool.
Every pin on C1 wired to the matching pin on C2, with the Route command exited.