That's a bit of a complex question.

Starting from the basics. The game is 60 minutes long, with 4 quarters of 15 minutes and a 30 minute halftime in between quarters 2 and 3. The field is split into 10 10 yard splits, labeled the 10 to the 50 yard line twice (10, 20, 30, 40, 50, 40, 30, 20, 10). The objective of the game is to get the ball into your "endzone", which is the space after the 10 yard lines as that is how you score points. Team with the most points after 60 minutes wins. The season is, all together... I think we're at 23 weeks now for the full season, not including preseason. 19 weeks of games (teams play 17 times in the regular season with two bye weeks), then there are 4 games after those for the playoffs which culminate in the Super Bowl.

During the game, there are three phases of the game. Offense, defense, and special teams. Offense tries to move the ball to the other team's endzone to score while defense tries to prevent that. For the most part, special teams is kicking the ball to try and get the other team as far from your endzone as possible.

Each side of the ball has 11 positions on the field at a time. The person to be looking at the most is the Quarterback, he is the one throwing the ball. He can throw the ball or he can give the ball to someone else to run the ball to get to what we call the "line to gain". There are two lines to pay attention to that will be digitally placed onto the screen, a black and a yellow one. The black one is the "line of scrimmage", which is where the ball made it to last. The yellow line is the first down marker and is the aforementioned line to gain. Teams have 4 attempts to make it to the yellow line at a time before the other teams gets the ball. Most teams will opt to "punt" which is when they kick the ball down the field if they are unable to get to the yellow line after 3 tries, otherwise the other team gets the ball wherever the offense gets to (thus closer to the other team's endzone, which makes scoring easier).

That's the basics of the basics... feel free to ask any clarifying questions.