when you win the league championship, you will promote to a higher division. right now you are in division "V", league "3"- hence V.3. promotion will put you in a division IV league. on the menu on the left, click USA, then 'complete league list' and you will see the structure of divisions and leagues in the US.
furthermore, in division V, you may promote also by simply finishing near the top of your league, through 'bot clean-up'. so division V is not hard to promote from, division IV is where the real game begins.