Pathstab at the top
New Itemicon (second one, looks like a little square)
Keywordstab at the top
__(that's underscore underscore), press enter
_e(that's underscore e), press enter
Update Summary window should display, with a list of strings that were found to translate, based on the keywords supplied above (__ and _e). Click Okay.
Save the .po file, and exit the program.
Make the .po file available for download (or optionally include it in the plugin archive). Translators will use this file to construct a .mo file, which will be used by the