To unlock the first challenge map, you need to earn a gold medal on Level 1-1, 1-2, 1-3, 1-4 and 1-5 (all levels in the first area).
After that, start up the challenge map and try hit all of the 10K icons as this will make you go up and down eventually getting a daredevil medal and some other medals as well.
Try to hit as many icons as you can, and as long as you get to the end of the course without hitting an obstacle and hitting 8 shot icons, the achievement will pop.