> my question is, Here **account system** is creating newaccount. So this **system account** must have some EOS balance to pay money that is written into the above command?
As far as I understand the user ‘eosio’/’testtesttest’ is creating the account. This account should have founds to be able to buy the ram when creating the new account.
> This system command could be on any exchange or wallet out side of my node?
I am not sure about this.
> then while using this command, i should use test account and its public key as owner?
Yes since you are creating a new account from ‘eosio’/ ‘testesttest’ public key. You will have control over this account as the author.
> and then we are done with main net?
As far as creating the account. I think so.
> BTW what main net URL should be used for this purpose?
I don’t understand the question. As long as you are running your node you should be connected to the main net/test net. I have not come across any documentation where you have to specify the main net url when creating the account.