Basic format:
Author, A. (Year, Month Day). Title of work.. Website name. URL
Example:
Scallan, M. (2015, August 25). Tattoos: Telling stories in the flesh. Smithsonian Insider. http://insider.si.edu/2015/08/tattoos-telling-stories-in-the-flesh-qa-with-lars-krutak/
If there is no individual author listed, substitute the title of the website. If there is no date of publication, use (n.d.) which means "no date" where you would put the date. Do not use the copyright date of the website as a publication date.
Example:
Monterey Bay Aquarium. (n.d.). Seafood Watch Northeast Consumer Guide. https://www.seafoodwatch.org/-/m/sfw/pdf/guides/mba-seafoodwatch-northeast-guide.pdf?la=en