We can draw the image formed by an object through a convex lens by drawing two lines.
Line 1 goes parallel from the object to the mid-line of the lens then continues through the focal point on the other side.
Line 2 goes from the object straight through the mid-point of the lens and continues on. See the animation below.
Where the lines meet is where the image is produced.
Click to see how this is done.

View the animation and click on the links below to see how the rays are drawn to form the image.

As the object approaches the lens from the right, as shown above, an image is formed on the left which is real and inverted. The image changes as the object approaches the convex lens. An object far away from the lens produces a real image (light actually meets to form the image), inverted and reduced. Click for more information

When the object is two focal lengths away from the lens the image appears inverted, same size as the object and two focal lengths away from the lens.

As the object approaches closer to the focal point the image produced is magnified and inverted. Click for more information

When the object is at the focal point no image is formed.

When the object is within the focal length of the lens the image is no longer on the left of the lens but appears magnified, upright and on the same side as the object. This image is known as a virtual image. Click for more information