Cheers mate appreciate thatThe scoring is a little bit like rugby
3 points for a field goal (aka. a penalty in rugby)
6 points for a touchdown, 1 point for the kick afterwards.
American football is all about getting 10 yards, you have 3 attempts to gain 10 yards, this can be done by either throwing the ball or running with it.
The first chance at gaining the 10 yards is known as '1st and 10', if they decide to run with it and gain 5 yards, then the next play is '2nd and 5', if they then throw it and gain 2 yards then they're '3rd and 3', lets say they then decide to run it and the player gains 20 yards then they'll have the ball further up the field starting at '1st and 10' again from wherever the runner got to before being tackled.
A team can lose ground on their plays though, for example if they're '1st and 10' and the defence tackles the player with the ball 2 yards behind where they started then the offense's next play will be '2nd and 12'.
However if the team fails to get the 10 yards then they will tend to either punt the ball away leaving the other team with bad field position or kick a field goal if they are close enough to the posts.
If a player drops the ball and the other team pick it up then the other team get the ball from wherever he dropped it. Also if one teams quarterback throws the ball and it's caught by a defender on the other team then the other team get the ball.
I think that pretty much covers the basics, if there's anything about that that you don't quite get then just let me know.