I have imported a Midi-file into renoise, see the notes but do not hear anything. Would be nice if you could help me!

Renoise imports the Midi file, but you have to configure the instruments aftwards. If you want to have a quick test, just rightclick on the file in Renoise diskbrowser and select “Load file with options”. Then in the dialog that pops up select e.g. the Microsoft Wavetable synth as midi device and then check the box “Create instruments” box.

You should have a midi file import that plays right out of the box. the instruments are perhaps not to your needs, but you can exchange them for instruments you find better fitting.