Each user must register for a SciFinder account here and keep track of their username & password. SciFinder is a research discovery tool that allows you to explore the CAS databases (American Chemical Society) that contain literature from many scientific disciplines, including biomedical sciences, chemistry, engineering, materials science, agricultural science, and more!
Free software download for students after you register for an account.
You can also use non-chemistry tools for rough mockups, such as Microsoft Word or Adobe Illustrator. There are other more advanced drawing software online, often requiring a paid license.