Write the persons name then in brackets (Write personal communication the date it happened and the year). Close brackets then describe what the conversation was about.
Referencing is very easy in APA format. This is the website that can guide you about APA referencing for any person in research papers and materials. So you can check this website to get related contents.
www.liunet.educwis/cwp/library/workshop/citapa.htm
www.liunet.educwis/cwp/library/workshop/citapa.htm