"..." - Select a file
"Process" - Reads the file
"Save temporary modified variable" - When you've made a change to a variable that you want to keep in your outputfile, you'll need to save it to memory by pressing this button.
"Save" - Saves your modifications to a output-file.
"Add variable" - Add a variable.

To remove a variable, simply remove all the data so that the size becomes zero.

Happy editing. Please remember that modifying the GDFS can destroy your phone! Especially if you modify checksummed variables (SIM-locks etc).