The files in the sources directory are used to rebuild the binary format files for Textures. The general procedure involves 1) Turning off Flash Mode 2) Opening the file to be "dumped" (converted to a binary file using the \dump command) 3) Selecting the format to be dumped on top of (For LaTeX, this means choose VirTeX) 4) Choosing typeset (command-t) 5) When the dialog box comes up, navigate to the right place to save the format (in the upper-left box, find your TeX formats folder and open it), give it a name. 6) Quit and then restart Textures. For more details see the Textures User Guide.