Once it is clear who has the initiative, all act in turn. The highest initiative goes first, then the next highest, and so on, until everybody has acted. You may perform only one action during your turn. An action may be an attack, a parry, an evasion, drawing a weapon, reloading a crossbow, diving behind a rock, running five meters towards an enemy, etc.

Once you have performed your action, your turn is over. So if you have to parry an enemy sword with your own, you cannot attack the enemy in this round any more!
There are only two exceptions to this rule:

1. If you have a shield and a weapon, or a left-handed and a right-handed weapon, you may actually make a special
   combined manoeuver: a parry and attack, a double attack, or a double defense. You roll separately for each action.
2. If you have used up your action already, and are attacked (again) in a round, you may ‘borrow’ the action of your next round to defend. In that case you give up your initiative, and come after all your current opponents in the next round.

Fridleif charged the dark werewolf, and chopped at the beast with his axe. But he missed. The wolf saw its chance and clawed at Fridleif ferociously. Fridleif had to duck quickly, losing his initiative, and the wolf now came upon him again!
(Fridleif ‘borrows’ his action from the next round to duck the blow, and thus loses the initiative in his next round to the wolf).