The Voting
Now you have to pay attention because it's getting a bit difficult: We will have three rounds of voting tonight. First, all eight acts will perform one song each. After that, the public will be asked for their opinion the first time: Only the four top-placed acts in the televoting will move on to the second round.
Those four acts will then sing their respective second songs, after which it's time for the televoters to decide once again. This time, only two acts will proceed to the third round of voting. And this very round will be the decisive one!
Out of the two remainig acts, the public will pick the one who will be flying the German flag in Copenhagen. At the same time, they will decide which one out of their two songs is the most suitable for the Eurovision Song Contest stage.
Source: eurovision.tv