Looking for a Script, or Action, or a Preset to divide 24 x 12 in PSD files into two 12 x 12 JPG files

I am looking for a script, or action, or a preset that I can use to divide 24 x 12 inch PSD files into two 12 x 12 JPG files that will save these jpg files into a folder for uploading to a book printing website.  I'm relatively new to PS so was wondering if anyone could point me in the right direction?   Thanks