Plugin translations, specifically Friends and Messaging

Hi,

I would like to translate at least two plugins Friends and Messaging and would like to know how to do that.

I see that both plugins have the _e and __ included and I already created the .mo and .po files, but I am not sure what to do now...

Please let me know if it is possible to use .mo and .po files and if so, how.

Thanks,
Paul