Please help with x and y movement

so i am making my first game, in other words, i am a noob. i want an enemy to come towards me. so to do this, i compare the x and y values.
cir is one of my objects names. enemy is the others’.
so on the enemies actions, what do i right,
onClipEvent (enterFrame) {
if (???_x > _x) {
_x + 3
}}
how do i reference another objects x and y coordinates.