There is usually going to be six players on the ice (unless there is a power play)
Here are the positions on the ice:
Goalie: Extremely important to a team. His job is to protect the net at all costs and he is in the crease the entire game. A good goalie can determine the game's fate.
Defensemen: Usually two are on the ice and they can score goals but they also can specialize on defense. They help out the goalie the most by always being towards the back of an offense attack in case the other team steals the puck and goes toward their offensive zone.
Right Wing: Usually on the right side of the ice (shocker!) and moves around a lot in the offense zone because they score goals.
Left Wing: Same as the right wing except that he needs to be on the left side of the ice (double shocker!).
Center: This player has to be good at his position because he's usually placed in face-offs and also scores goals for the team.
Below is a visual of how offense is supposed to look like (Note: Offense does not always look like this)
One century of this game and League is a wonderful milestone to celebrate. Let's hope to do this in the next century!