Your English is fine.
avast currently doesn't have an on-line submission only the email submission and submission from the avast chest, suspect files added to the User Files section (File, Add), they can be selected to send to Alwil and they are encrypted and also emailed.
I don't know if files scanned on the online.avast.com would be further analysed if on initial scanning nothing was found. But, it certainly would be an opportunity to keep a copy that is submitted, I just don't know.
Samples sent to VirusTotal and Jotti that aren't detected by any of the AVs should eventually be forwarded to those AV companies, how reliable this is I can't say, I'm only an avast user like yourself.
There are apparently considerations on improving the submissions possibly including an on-line submission, but I have no idea when or if this will happen.