hitTest with gravity

programming flash
1

so my game’s code is as follows:

//The Austin Weisgrau (El Nacho)
//Blob Game, to go with the video so it will get like the .3 mor it needs not to be blammed
stop();
Blob_Movement = {x: 0, y: 0};
World_Gravity = 1;
function Blob_Slowdown(){
 Blob_Speed *= .9;
 if(!Key.isDown(Key.LEFT) && !Key.isDown(Key.RIGHT))
 {
  if(Math.abs(Blob_Movement.x) <= 1){
   Blob_Movement.x = 0;
   Blob.gotoAndStop(1);
  }
  else if(Blob_Movement.x <= 0) Blob.gotoAndStop(4);
  else if(Blob_Movement.x >= 0) Blob.gotoAndStop(5);
 }
}
onEnterFrame = function(){
 if(Key.isDown(Key.LEFT)){
  Blob.gotoAndStop(3);
  Blob_Movement.x -= 4;
 }
 if(Key.isDown(Key.RIGHT)){
  Blob.gotoAndStop(2);
  Blob_Movement.x += 4;
 }
 Blob._x += Blob_Movement.x;
 Blob._y += Blob_Movement.y;
 Blob_Movement.y += World_Gravity;
 
 Blob_Slowdown();
 /*
 while(Background.hitTest(Blob_Movement.x+_x, Blob_Movement.y+_y, false))
 Blob_Movement.x -= Math.abs(Blob_Movement.x)/Blob_Movement.x;
 while(Background.hitTest(Blob_Movement.x+_x, Blob_Movement.y+_y, false))
 Blob_Movement.y -= Math.abs(Blob_Movement.y)/Blob_Movement.y;
 */
 /*
 if(Background.hitTest(Blob)){
  Character_Movement.y -= math.abs(Character_Movement.y)/Character_Movement.y;
  Character_Movement.x -= math.abs(Character_Movement.x)/Character_Movement.x;
*/
 }
 
}

the character instance is Blob and the background instance is Background. i can’t get the hitTest to work with either of those two things in the /* */ and i need to no how i can