I found the championship first level rather hard? I still havent gotten first? What am I doing wrong.

I know, it took be forever to beat it.

if you mean the race in paris it took me 2 trys, try use drifts with a combo of tapping the accelerator around those tricky turns, it doesnt lose hardly any speed and lets you keep control, just dont boost during this you may lose control.

The first one I did first time (amazingly).
At that roundabout near the Arc de Triumphe just let go of the B button and drift round - as long as you did well in the other bits you'll win by miles.
Another tip - whenever you see a straight, use the boost. I suggest using it just after the 2nd bridge.