Looking at a picture of the D3200 it looks like the outputs are the pairs of quarter-inch jack sockets at the top centre. Just to the right of the Mic input sockets. Labeled Monitor L,R and Master L,R.

The owner's manual at http://www.korg.com/downloads/pdf/D3200_E1.pdf
shows them in "Parts and their Functions" on page 16, items numbered 7 and 8.

Mitch