By default, our templates use English (en-GB) for their text. To make translation, you simply need to create a new directory for your language encoding, e.g. de-DE for Deutsch language, in the template purchased's language directory which is located in:
your-joomla-directory/templates/template-installed/language
After that, copy the file en-GB.tpl_template-installed.ini from the directory en-GB to the newly created directory then change en-GB in the file name with your language encoding, e.g. de-DE.tpl_jez_rego.ini for Deutsch.
Now, open the new language file with your favorite text editor and start translation.