It's impossible to understand, really, unless you grow up with it. But basically:
Like baseball, you're trying to score runs. You've got two batsmen at once. They score runs either by hitting the ball to the fence, or by hitting it into the field, and running to the other end of the pitch. (So basically like running a base in baseball, kinda).
If the bowler (pitcher) bowls the ball too wide of the batsman, the ball must be bowled again, and the batting team gets an extra run.
The batsman can be out caught, or bowled (if he misses the ball and it hits the sticks behind him) or run out (if he tries to make a run, but a fielder hits the sticks with the ball before he reaches them).
The batsman does not have to run if he hits the ball, and can bat as long as he likes (he can't be 'struck out').
Each team has 11 players. An innings ends when 10 members of the batting side are out.
There are no foul zones like in baseball - you can score runs anywhere on the field.
Each side would usually use between 4-6 bowlers in a game.
That's simplified - there are some time restrictions on how long you can bat, but at the simplest level these don't matter. There are also lots of other ways to get out, but I've listed the main ones.