I can''t tell you of a place to find this information, but I do have a few ideas.
1.) Make some rules for the different positions, such as forwards stay between a certain area during gameplay.
2.) Keep each player on his part of the field so he won''t interfere with the other players of his position. Relate this to number 1.
3.) When the ball comes into a player''s area, he tries to gain possession of the ball (by running straight for it)
4.) For strategy, locate the positions of the enemy players and make some sort of pathfinding algorithm to determine both the shortest way and the best way to get to the goal (best means farthest from the enemy)
You can do the first two with just x,y coordinates, three is just as simple. Four is obviously the hardest and worst idea I''ve given you.