Hi Philippe,
Thank you for your question, and your english is excellent, much better than my French.

I'm assuming that you're trying to recreate what we did in this
blog post. Although, all of the source code is there for that, it's probably a bit over complicated, and definitely not that well documented, as it was very much thrown together for the workshop we were teaching.
One thing I've realised since writing the blog post is that you don't really need the mini driver (although it's still a very useful board), everything can actually be done with the Seeeduino. The basic hardware configuration is that you place the Raspberry Pi on the robot, and then power it with a USB powerbank. Something like
this one. Then you connect the Seeeduino to the Pi using the USB cable that comes in the kit.
That essentially is all there is to it on the hardware side. You now need to write a motor control sketch for the Seeeduino, that listens for serial commands that come from a control program written for the Pi. There are examples of both the sketch and the control program (written in Python) linked from this
blog post, and our Pi Camera Robot
blog post.
Does that make sense? Also, how confident do you feel with Arduino programming, and/or Python programming? As I can provide further pointers there if needed.
All the best.

Regards
Alan