Hi,
You will need to declare self employment and or partnership gross profit and expenses on SA103 and or SA104 or their equivalent on the online return.
Only then can class 4 NIC be calculated and added to the liability. You also need to contact the NIC helpline on 0300 200 3500 (Monday to Friday: 8am to 6pm Closed on Saturdays, Sundays and Bank Holidays) to register as self employed and to pay class 2 NIC directly to them for 22/23.
You can find more information at:
National Insurance: detailed information
Thank you.