Postdoctoral positions are arranged directly with the mentor, and are not processed through a central administration. Select a mentor and contact that person directly about arranging for a postdoctoral position. The mentor is the person who determines the availability of positions in his/her laboratory.
Funding for positions is also arranged through the individual mentor. Most often funding comes from the research grants of the mentor. In some cases, the mentor may nominate you for support on a training grant on which he is a participant (you cannot nominate yourself). He may ask you to submit an individual NRSA grant.
Information on possible mentors, and how to contact them, can be found in the faculty in the faculty research interests section on the Department of Molecular Virology and Microbiology site.