I love ice hockey but just started watching last season. I don't understand it all yet. 
I see, well its a simple game really. Two teams compete to shoot a rubber puck into the opponent's goal to score points!
That does sound easy. How do they get a penalty? I have seen people go to the box but unsure why. 
Its due to foul play by the opposition, sometimes when a move is seem as being too fast-paced and physical, the referee gives a penalty!
And how does overtime work, that still confuses me too!
Overtime is usually given for play beyond normal working hours for hockey players. Usually due to interruptions in the game that add up incrementally.
And then some players switch teams for playoffs? 
Precisely, these are in place in order to consider the players' health and productive play!
How long does a player play in a game?
Winning Streak
Winning Streak is an Irish television game show, Europe's second longest-running after the UK's Countdown. Aired weekly in Ireland, five contestants play a number of games to win cars, holidays, and cash prizes up to €1,000,000. 
Broadcast on Saturday nights between early September and late May on RTÉ One, the game show is among the channel's most popular programmes, often ranking among the top five in the ratings. However, there was a significant drop in viewership in the 2008/2009 series
Ice hockey
Ice hockey is a contact team sport played on ice, usually in a rink, in which two teams of skaters use their sticks to shoot a vulcanized rubber puck into their opponent's net to score points. The sport is known to be fast-paced and physical, with teams usually consisting of six players each: one goaltender, and five players who skate up and down the ice trying to take the puck and score a goal against the opposing team.
Ice hockey is most popular in Canada,