To be able to translate the plugin to your own language you will need to install Poedit which you can find on http://www.poedit.net/
When you installed that program download the file default.po from the folder translation (which is found in wp-content/plugins/tradetracker-store/ on your webhost) After the download double click the file.
You will now see all English phrases. When you click on a English phrase you will be able to write the translation of the sentence. When you are done with the translation go to file and choose save as. The name you will have to use is: ttstore-nl_NL.po change nl_NL to the language you used. So es_ES for Spanish, fr_FR for French etc etc.
You can also send your translation to firstname.lastname@example.org then i will add it to the plugin.