Here are some basic plays when your on the field.
1st base: If the ball comes to you tag the bag. If there is another runner, and you feel confident in your throw, throw to another base to get a double-play.
2nd base: ~ If the ball is on the right side of the field( coming towards right field)
Go one with a soft toss, or tag the runner going by
~ If the ball is on the left side
You cover second base. If the ball is infield, you stand on the corner of the base facing the pitcher. If the ball is outfield stand on the corner facing the outfield.
If the ball is coming towards 1st you need to back them up.
Short stop: ~ If the ball is on the right side of the field
You are covering second
~ If the ball is on the left side
You are fielding the ball, going 1st,2nd( if there is a runner), 3rd (if there is a runner) or home( only if you can beat the runner there)
If the ball is coming towards 3rd you need to either cover them or cover the base( usually on bunts)
3rd base: If the ball comes to you, go 1st, tag your bag (only if a runner is coming), toss to home (only if runner), or go second( only if runner)
Right Field: If the ball comes to you go 1st. You will be responsible for backing up the throws made to first.
Center Field: If the ball comes to you, throw it to second. While the ball is in the infield, you are responsible for backing up throws to second
Left field: If the ball comes to you, throw into second or pitcher( just to get the ball in), or if there is a runner toss to third.
*on a steal: to second: the short stop will cover the base and the second base will back up the throw or shadow ( follow behind the runner) at second
: to third: the third base man will cover third, short will back up the throw, second will stay on second incase the runner turns and goes back.
*On a bunt the third and first basemen will have to crash on the ball. Second will cover first, centerfield will cover second, and short stop will cover third.