It's not easy for a greenhand to look at 3D pictures by adjusting the eye point to something behind the object.The progress need to be made gradually according to steps mentioned below.

1.Put one finger in front of your eyes(the distance appro.25 cm ),then look at object behind your hand,such as the groud .Now you should find that your finger has changed as if becoming two.

2.Then put out two parallel fingers(appro.3cm between )with your eyes looking at the ground,so that you feel your two fingers become four,now try to make the middle two fingers moving together with your eyes,and your will see three fingers.

3.Draw two circles on paper(appro.3cm between),just as what your did just now,adjust your eye point to something behind the paper,trying to integrating the middle two circles.
After finishing the practice above,and if you have passed them all,then your can read 3D pictures well with the same method.But remember,make sure that the picture be parallel to your eyes ,or you'll never succeed .However, it will not matter if you turn the picture 180 degrees about an axis ,so you can have a try if you wish.

One more point,it will never affect your practice if you are shortsighted.However,if your two eyes differ greatly in sight, you'll have to take that into account by adjusting the distance between eyes and paper,so that you can see the picture clearly,instead of finding it clear one side and dim the other.Ok,wish you every success. (Pls remember that do not look at such pictures for too long, or it 'll do harm to your eyes)