how to implement predictive modelling algorithm in C#

Carefully.


Basically, the same way you do any other project:
1) Specify it
2) Design to specification
3) Code to design
4) Test against specification
5) Depending on the results if 4, may repeat from stage 1, 2, 3, or 4.

So, decide what predictive modelling algorithm you want to use: Google[^] and work from there.

We do not do your homework: it is set for a reason. It is there so that you think about what you have been told, and try to understand it. It is also there so that your tutor can identify areas where you are weak, and focus more attention on remedial action.

Try it yourself, you may find it is not as difficult as you think!