You always need to give credit for where you got your information. You have had lots of practice doing this through quoting in other writing, but you also have to do in-text citations when you use your own words, but got the information from another source.
Here's how to do an in-text citation:
At the end of a paragraph in which there are no quotes, you add the author & the year of the resource. For example:
Koala bears are native to Australia. They are marsupials like kangaroos (Smith, 2008).
If there is no author, you add the first word from the references page, which will probably be the title of the webpage. For example:
Koala bears are native to Australia. They are marsupials like kangaroos ("Koalas", 2008).