Well, glad to see you are interested to contribute our translation project.
#1. First you need to download and install poedit available free at https://poedit.net please watch available video tutorial for poedit at youtube.
#2. Please download question-answer.po from here https://plugins.svn.wordpress.org/question-answer/trunk/languages/ and open on poedit.
#3. Save as your .po using following rule
Please see the available language and country code bellow link
#4. And edit translation for your language.
#5. After finish translation please send it to via our contact page
#6. we will review your translation file and added to new plugin release.