If the movement is side to side it is most likely an inner or possibly outter tie rod gone bad.
Jack the car up & support it with jack stands. Have a friend shake the wheel side to side while you get under & try to feel which part is causing the movement.
If it's the inner tie rod, you need a special tool to remove it & install the new one. Best left to a shop for this one.
If it's the outter tie rod slightly loosen the jamb nut attaching it to the inner tie rod. Remove the nut on the stud at the steering knuckle, unscrew the tie rod off the inner tie rod. Installation is the reverse of above. Now go get an alignment!!!