Referencing work is important because it's useful for others to know where you've got the information from. This not only helps them find the source, but also ensures that the author of the original work gets credit for your ideas. A good reference list involves the author, date of publication, company, and for web resources, date accessed. This makes it easier for someone to verify the claims made on your work.
How to reference?
To reference, you will need to note which resources you used. For web resources the URL and date accessed are the most important points, and will allow you to find the reference for full referencing. Having the book title and date published, or basic information to re-access the resource is always helpful. Use a service like Cite this for me or a similar referencing tool for an easy way to reference.