The Translation Index tab is a simplified version of what you are used to seeing in the main Index tab. On the left you will see a list of keywords and as you click on each one the Original and the Translation text will appear in the middle. Simply translate the text for each Keyword and click the green Translation Status to show that is has been completed. You should then end up with an Index that looks something like this:-

See Next

Translating Variables

Translating Documentation

Translating the Website

See Previous

The Status Tab

Translating the Help Text

The Translation Environment

Translating a Sample Project