I don't know what you previous shooting experience is, but lets walk through this and see if we can isolate whether it’s a gun problem or a marksmanship problem.
The first step is to ensure all screws are tight; this includes the base mount screws, the screws in the rings, and the action screws that hold the stock to the barreled action. It sounds as if you have the style of mount that can be adjusted for windage at the rear of the mount and the ring locks in the front of the base mount in a dovetail. If this is the style of mount you have, do not turn the ring into the dovetail with the scope; it must be done with a wrench. If you turned the mount into the dovetail with the scope tube it is possible you damaged the scope. If you turned the front ring into the dovetail with the scope tube, you should get a bore sighter with a grid like the Bushnell, and see if the scope adjustments move the cross hairs the correct amount. If not the scope will have to be repaired.
Next we want to set the scope for it's mechanical center. To do this, adjust the windage as far as the adjustments will allow and count the clicks as far as the adjustments can be moved. Now, divide the number of clicks by 2 and come back to that point and that is the scope's mechanical center.
Using the bore sighter, or bore sight by peering through the bore at a distant object, the more distant the better, and adjust the windage in the mount until the cross hair comes in line with the object you are bore sighted on. The rifle will have to be set in a gun cradle, either a commercial one or make one from a cardboard box that will hold the rifle snugly without allowing movement when you adjust the scope. Double check the object through the bore frequently to make sure nothing has moved. Don't worry about elevation right now, windage is the important thing.
Before you begin to live fire, try dry firing the rifle. At this time you will be able to determine if the scope is the coitrrect distance from your eye. You should be able to see a full sight picture without any shadows, and you should not have to slide you head around on the stock to get that full field of view. When you dry fire, watch the cross hair against the target and see if it moves off the target when the firing pin drops. If it moves even a hair, you need to work on your trigger control, breathing and follow through. It is possible that the trigger needs adjustment, either to lighten it, to reduce creep, or to reduce over travel. A good dry firing drill is to place a quarter on the top of the barrel near the muzzle and attempt to dry fire without disturbing the coin. When you can do that, you are ready to begin live fire.
Starting at 25 yards as you did was correct. This time, set the forend of the rifle on a sandbag, and put a second sandbag under the butt. A sock filled with sand works well under the butt. Because the rifle is a sporter, you will have to hold the rifle firmly when you fire, or it will throw the shots wide. Keep your support hand between the sandbag and the forend. You firing hand should have a firm, but not death grip on the pistol grip, and the first pad of your trigger finger, just below the fingertip, should engage the trigger. Take a couple of deep breaths, relax, place the cross hair on the bull, hold your breath at the natural pause between inhaling and exhaling and press the trigger. If the shot does not break within 5 seconds, stop and begin again. When the shot goes it should surprise you, but stay on the rifle and regain your sight picture. This is called follow through. Without getting out of position, work the bolt, moving your head just enough to prevent being hit by the bolt, then fire a second shot following these same steps, then a third. Check your target, and you should only have to make an elevation adjustment and perhaps a very minor windage adjustment. Leave the windage adjustment until you fire a 100 yard group. The bullet holes at 25 yards should form a single ragged hole.
Go back to 100 yards and fire another 3 shot group. Adjust the scope as required. Your group should be 2.5" or less. If possible fire a group at 200 yards and zero the scope to hit point of aim at that range.
The next time you go to the raqnge, check to see if the rifle shoots to the same point of aim. If not, was it becasue of anenvironmental change, (wind or temperature) or did something change with the rifle. If it was the rifle, that is a problem that should be addressed.
Now get off the bench, and begin shooting from field positions.