How to translate USC package descriptions?

Hi!

In Launchpad we get the option of translating Ubuntu Software Center, but I couldn't find a way to translate package descriptions that appear on it. In my language, there are a few packages translated and a lot more in english, but Launchpad tells me that its translation is complete: https://translations.launchpad.net/ubuntu/oneiric/+source/software-center/

How can I contribute to USC descriptions?