Use molecular models to build the 3D compound. You can purchase the molecular model kits online or at a book store. In the kits, there are different balls and sticks to represent each of the atoms and bonds. For example, you may be making ethane, C2H6. The black balls may represent carbon and the white balls may represent hydrogen. Therefore, you put one stick at the end of each of the six white balls and a stick between both of the black balls. You then attach three white balls to the one black ball, and the three other white balls to the other black ball.
Use a dark wedged line to represent the bonds that come out of the page, use solid lines to represent the bonds that are in the plane of the page and use dotted lines to represent the bonds that are behind the page.
Draw the compound using the three different types of lines. For example, when drawing ethane, C2H6, put a dark wedged line in front of both carbon atoms, put a solid line to the side of both carbon atoms and between them, and put a dotted line behind each carbon atom. Write an H at the end of each of the lines.