Simply use it to open Dictionary.xml or Code\local\ConfigMsgEN.xml and once loaded you are prompted to load your current translation of it or you can create a new translation.
Make sure you chose the correct 'To' language in the drop down box at the top.
N.B. Google Translate option should only be used for plain text values. It does not work well with parameterised phrases i.e. containing {n} and { } | etc. The automatic translate adds extra spaces and removes some brackets making the phrase syntactically incorrect.