An important aspect of communication in chemistry, especially organic chemistry, is the ability to draw chemical structures. Students learn how to represent structures in different ways (Lewis structure, condensed structure, line structure, and 3D structure) on the 2 dimensional page. As computers have become more important in this process, it becomes important to be able to represent these structures on the computer. An "old fashioned" way would be to draw the structure by hand, scan it, and convert it to an image such as a gif file. A much better way is by using a computer program designed to draw the structure.
LON-CAPA uses the JME Molecular Editor for the task of drawing structures in response to questions. (It is used because it can convert your structure into a unique "string" that can be evaluated by the computer).
To begin, go the the University of Southern Maine's tutorial page for instruction on using this editor and for practice. When you think you have the hang of drawing the structures, then proceed to the homework problem. To answer a problem, click on the "Draw Molecule" button, then a new window appears with the editor. (You must have Java installed and enabled for the editor's applet to load. It may be slow loading the first time.) When you have finished the structure, click on the "Insert Answer" button, and the applet inserts the unique smiles string into the text box. Then click on the "Submit Answer" button.
If you are familiar with Java Applets, you can obtain a copy of this program from its author, Peter Ertl, install it on your computer, and practice with it.
A number of rather sophisticated chemistry drawing programs have evolved in recent years that not only can show a structure, but some can store chemical information about the structure (is it chemically correct?) and some can even draw structures from names and derive names from structures. Some of this software is pretty expensive. ChemDraw, for example, is a very popular but quite expensive, though discounts are available for students.
There is some free software available, however. Examples include:
ISIS Draw from MDL
DrawIt from BioRad
ACD/ChemSketch from Advanced Chemistry Development, Inc.
You might want to download one or more of these programs to try out.