Here is the screen showing you the level (node) you are about to play, and it will also show you your high score to the right if you've played the level.
You start off manuevaring around the level trying to go all the way around these white cells. You have to go around all of them, turning the white into color, to get 100% and complete the level. That rectangle that you see at the top right of the big cell is an enemy that moves in a predetermined path, in this case up and down.
You have to watch out for the enemies. They're faster than you. Those brackets surrounding the line there to the right of my character are crucial. You go into those brackets and you can detonate, making a blast radius that will hopefully destroy both enemies on the line (only for about 2 seconds), giving you enough time to finish that stretch of line on their path.
Once you clear all the area, a "doorway" will open up that you have to get into, still dodging enemies. There is a time limit to get the medals although you can still complete the level after the time limit is finished.
Finally, the post game screen. I didn't finish it in time, and didn't get any medals
You can view the leaderboards for people nearby, friends, and overall.