I used this website last night, first you need to register and obtain a password.
Once past that hurdle you simply answer the questions. For example name, address, passport number and date you last entered the country. Submit and wait for email.
BUT if first time report or new passport you need to apply in person
My neighbours went back in October 2019, been here 12 years and were told the same had to be done for next time. As it happens they never got round to next time as the wife is still stuck in Russia!