Board Game Arena

HI
Can someone tell me how to submit my code at the end of the game? I figured out the number (I am pretty sure) but couldn't figure out how to submit it. Please help. I know this is a me problem, not a game issue !

If you are the first to play you can’t submit a code.
When I am the seconde player, when the first player have the good code I can submit my code on the top of my screen. All the numbers are alligned on the top of the screen.
Maybe younare always the first to play?