Navigate to the CMS Home tab
Create a new Workspace if required (The workspace creation wizard let's you specify the languages, the contributors and the community that is associated with the workspace).
If you have not already enabled multiple languages, add one from the 'Languages' button on the Workspace home page. Flag an Article as 'Ready for Translation'
Navigate to the workspace and export all articles that are marked 'Ready for Translation'.
You will receive an email with a Zip file. Extract the Zip to find a file with a .xlf extension. Open the file in a XML editor (Wordpad / Winword etc for Windows and Textpad for Mac)
Update the TARGET attributes with the translated content.
Zip the file again. Import the translated content back into Salesforce.
View the translated content under the 'Translations' tab.