How to translate plug-ins?

Hello,

I have installed dozens of plugins and now it's time to translate them into my language. I have to use PoEdit for them, but before I start - can you teach me what to do on example of plugin "Blog Types"?

Should I edit these files:

blogtypes-default.mo
blogtypes-default.po

or should I create new files, for example:

blogtypes-default-ka_GE.mo
blogtypes-default-ka_GE.po

If so, from where will I be able to choose language. Same question about all translation-ready plugins.

Thank you