Use the Arrow keys to orient yourself in such a way that you have roughly a front view of the scene, and zoom out (.) so the circle isn't filling much of the screen, perhaps only about 20 percent. Hold the CONTROL key down and then use the vertical (up/down) arrow keys again, and you'll be moving the camera up or down. Make the circle get close to the bottom of the screen so there's much room left above the circle. We'll now do an extrusion, which will use the circle to make a bottle.

Select the Extrusion tool (six^th from the top in the Construction toolkit). Then click on the circle again. You're now starting to extrude the circle into a cylindrical shape.

Hit 2 for a front view. Adjust the view with the arrow keys as needed. Start creating the shape of a bottle, section by section, clicking a few points up. If you mess up, undo with BACKSPACE.

In order to force the sections along a perfect vertical alignment, hit the SPACEBAR. This toggles the red/green axes to go from both to one or the other axes. After a few clicks, you'll have something resembling the image below, and you'll be working your way up to the bottleneck.

When it's time to start moving inward, break out of the vertical motion lock by hitting the SPACEBAR again until both axes are shown again and keep moving freely. If you don't like the granular 'snapping' to grid positions and prefer to move the cursor totally freely, just increase or decrease the sensitivity of the grid lock with the +/- keys.