To be able to attend to WOF online tournaments, you need to be WOF-verified. On your profile at Vint.ee or eOthello.com you can see if you are WOF-verified. 
If you are not WOF-verified, use the registration tool here and send a request to be verified. 
We will contact each federation to check if a player can be verified or not. 
If you have any questions, please contact your national federation