The links below describe in detail how to use either Harvard or Vancouver referencing styles for writing an essay/thesis. Harvard is probably the easier to use especially if you don’t have a reference manager program. This is due to the fact that it is very forgiving if you need to add additional detail to the article. Instead of having to re-number ever reference if you used Vancouver style, you can just add the surname and year to the new reference and just put the references in alphabetical order at the end of the article.
The most important thing to remember with referencing is to be consistent with what ever style you use. Use of web links is never appropriate for referencing!