The Purdue Online Writing Lab (OWL) contains citation examples and instructions. Take a look at this resource for extensive examples on how to cite your sources and in-text citations.
List as much of the following information as possible (you sometimes have to hunt around to find the information; don't be lazy. If there is a page like http://www.somesite.com/somepage.htm, and somepage.htm doesn't have the information you're looking for, move up the URL to http://www.somesite.com/):
Author, A. A., & Author, B. B. (Date of publication). Title of document. Retrieved from http://Web address
Angeli, E., Wagner, J., Lawrick, E., Moore, K., Anderson, M., Soderland, L., & Brizee, A. (2010, May 5). General format. Retrieved from http://owl.english.purdue.edu/owl/resource/560/01/
NOTE: When an Internet document is more than one web page, provide a URL that links to the home page or entry page for the document. Also, if there isn't a date available for the document use (n.d.) for no date.
To cite a YouTube video, the APA recommends following the above format.
Author, A. A. (Year, Month Day). Title of article. Title of Newspaper. Retrieved from
http://www.someaddress.com/full/url/
Parker-Pope, T. (2008, May 6). Psychiatry handbook linked to drug industry. The New York Times. Retrieved from http://well.blogs.nytimes.com/2008/05/06/psychiatry-handbook-linked-to-drug-industry/?_r=0
Online articles follow the same guidelines for printed articles. Include all information the online host makes available, including an issue number in parentheses.
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Online Periodical, volume number(issue number if available). Retrieved from
http://www.someaddress.com/full/url/
Bernstein, M. (2002). 10 tips on writing the living web. A List Apart: For People Who Make Websites, 149. Retrieved from http://www.alistapart.com/articles/writeliving
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Journal, volume number, page range. doi:0000000/000000000000 or http://doi.org/10.0000/0000
Brownlie, D. (2007). Toward effective poster presentations: An annotated bibliography. European Journal of Marketing, 41, 1245-1283. doi:10.1108/03090560710821161
Wooldridge, M.B., & Shapka, J. (2012). Playing with technology: Mother-toddler interaction scores lower during play with electronic toys. Journal of Applied Developmental Psychology, 33(5), 211-218. http://doi.org/10.1016/j.appdev.2012.05.005
Online scholarly journal articles without a DOI require the URL of the journal home page. Remember that one goal of citations is to provide your readers with enough information to find the article; providing the journal home page aids readers in this process.
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Journal, volume number. Retrieved from http://www.journalhomepage.com/full/url/
Kenneth, I. A. (2000). A Buddhist response to the nature of human rights. Journal of Buddhist Ethics, 8. Retrieved from http://www.cac.psu.edu/jbe/twocont.html