1) Extract stings:

 a) Generating a pot file:

   xgettext -L python ../src/sayhoo -o fr.pot --no-location
   Translate strings and save as fr.po

OR 

 b) Merge information from an exisiting po file.

    xgettext -L python ../src/sayhoo ../src/*.py -o tmp.pot 
    xgettext -L glade -j ../data/sayhoo.glade -o tmp.pot

    msgmerge -v fr.po tmp.pot > fr.pot

    Translate fr.pot
    mv fr.pot fr.po

    commit your changes.

2) Generate the mo file.

 ../tools/msgfmt.py  -o ./mo/fr_FR/sayhoo.mo  fr.po


