1. to ROLL A CANOE-- is to paddle one in such a manner that the craft is actually tilted over sideways and then rolled 360 degrees on its long axis, so that the paddler rolls under water and then re-emerges on the other side as the canoe returns to upright (speaking usually of a kayak, actually, I think, in which this is relatively much easier to do than with a canoe proper). It is training to control one's canoe well against the possiblility of accidents. Is that clear?

2. THE BURN OF CONCENTRATION is a metaphor taken from the physical 'burn' of the muscles when exercised strenuously, as with the quadriceps in bicycling or most of the large muscles in weight training. Here I suggest that it means no more than concentration itself-- when you concentrate on the learning itself, you forget the fear of danger or failure.

3. FEEL FOR THE COUNTRYSIDE -- seems to be a rather fanciful image (of what? mountain bikes? 4-wheelers?) which suggests that you can get physically and spiritually close to the natural environment that you are ploughing through in/on these vehicles.

Thanks, it's perfectly clear now (my biggest problem was 'roll a canoe').
The vehicles in question were different kinds really: balloons, canoes etc.