To start: klick at a word or start typing.
From: source language
To: target language (either a single one or "All" simultaneously)
Del: delete last word
Clear: start over
Random: generate a random phrase
Google translate: the current input and language choice; opens in a new window or tab.
The symbol &+ means binding of two words. It will disappear in the complete translation.
The translator is slightly overgenerating, which means you can build some semantically strange phrases. Before reporting them as bugs, ask yourself: could this be correct in some situation? is the translation valid in that situation?