This is the best site to check out APA citations, they have kept up with all the new changes.
In general, last name of author/s, year of publication, and if it is a direct quote then you have to put the page number.
If there's 2 authors, you cite both of them every time If there's 3-5 authors, you cite all of them the first time, and then only the first name and et al., from then on If there's 6+ authors, you only cite the first name and then et al.,
Go here: http://funadvice.com/r/14k13he1lum & in the top left corner, click APA. Then just follow the instructions and it will set up the citation for you :)
We also have a How To for that: http://www.funadvice.com/howto/writeapastyleresearchpaper