Scratch

I am currently trying to create two games. The first is a game that is almost like pong. The player controlls 4 directional paddles, fending off projectiles that are fired from 4 sprites that are moving around the edge of the screen.
The second is the player controlling a spaceship that fires at enemy ships attempting to reach the player's ship.
My problem is that in both games, i cannot work out how to make the enemy's fire at the player, or for the player to fire. Because in both games, the sprite that fires is moving, i cannot work out how to make it fire from it's new position. Anyone got any ideas?