what is our first and lest chromatic for Bb clarinet , in jazz what ascending and descending scales , how do u improvis

A chromatic scale is just a scale when you play all the notes possible. So a C chromatic scale would go
C, C Sharp, D, E flat, E, F, F sharp, G, G sharp, A, B flat, B, C.

Yeah.

And to ascend and descend It just means going up in a scale or going down in a scale.

To improvise you play whatever you want (note value wise) with a certain range of notes.