Making some assumptions as to how you want your enemies to move, the simplest approach would probably be:
1. Every frame, loop through the array, and for each enemy...
2. Determine distance between player and enemy using Point.distance or the distance formula
3. If within desired chase distance, point the enemy towards the player using the angle between two points formula
4. Move the enemy towards the player using basic vector movement
Working in "rotate towards" behavior and enemy movement acceleration would not be too hard either, check google.