Optionally, you can not tell anything about you person or even tell everything.
In any case, webmoney have full information about all payments in the system. In case of withdrawal of funds from the system they may require proof of identity (for Russian citizens is a notarized statement with your name, for example) or just save your name if you withdraw funds into bank account.
when you input money into webmoney system it can be done anonymously but later at any time the system can block the user's account to determine his identity (similar as in the derivation of funds)
details can be found here: