The most common action in a combat is the attack. The attack may be with a close combat weapon, such as a club or sword, or with a missile weapon such as a bow. Whatever the case, you always roll a weapon skill check for an attack. So, when you attack with your Short sword, you roll a d10, and add your Short Sword skill. To see if you have hit, and where, look up the result in the attack table below.

As you may note, you must make at least a 9 to hit someone in combat. That is because people generally try to avoid being hit. When you are attacking from behind however, surprising a victim, or hitting on someone who is down or held, you may add 3 to your roll, up and above your skill.

Mordred just flailed his morningstar on the troll from behind. He didn’t care if it was an attack in the back. He didn’t have any morals. And it was easier. The iron ball hit the monster right on the skull with a terrible crunch.
(He rolls a 6, adding morningstar 5, adding another 3 for attacking from behind, making a 14, or a hit on the head.)

If the Game Master? feels a victim is especially defenseless, he may give you a +6 instead, or rule that you kill automatically. If a victim is unconscious for example, and you have ample time to deal with him, there is no point in rolling the dice.