Translate Ubuntu

[Khoem Sokhem]

Hello List members,

I am Sokhem Khoem, currently a translation coordinator for Khmer Software 
Initiative Project. Now I and my team have translated many softwar into Khmer 
such as: OpenOffice, Firefox, Thunderbird, exelearning, Moodle, Drupal, 
Inkscape, Gimp, KDE (now about 70% of KDE are translated into Khmer), 
openSUSE and last year we have translated Debain installer but now it not up 
to date. 
Now we want to translate Ubuntu and Kubuntu into Khmer as well.
So I have some questions to ask:
1- where can I start ?
2- where can I get .po file(s) for translating?
3- how can I send the translated file(s)?

I hope to hear from you soon.
Thank for your reply!

Sokhem