Thankyou very much everyone :-)
Yes its a full improvisation, but i must say that the backing track was very easy. Its 4 bars of C-minor, then 2 bars of DbMajor and 2 bars of C-minor again. And repeat over and over...
The chords look like this :
//: Cm7 / EbMajor9 / Fm7 / D-halfdim /...