To load a (La)TeX file directly in jPreTeX, first open a
document (by "Ctrl o" or
by clicking on the open file button
or by choosing "open a document"
in the File Menu) ;
then click on the combo "Files
of type" and choose "TeX
files" ;
now choose the file you want.
jPreTeX
will translate this TeX
file (*.tex) in a new jPreTeX
file (*Bis.joc) and open it. You can modify this document then preview
it as usual. This will create a new TeX file *Bis.tex.