First time reporting online is not acceptable and have to go in person.You may submit and receive acknowledging mail but it's not enough. It has to be approved and mailed to you again.
Please contact me directly if you need. I did it last year and am preparing to do the same in August for another year. Everything depends on your concerned immigration office based on your address in Bangkok. Better you check go to the concerned immigration office, collect the check list and clarification.