What part of your foot do you use to dribble a soccer ball?

You use the inside of your foot to hit a soccer ball.

Players use all parts of the foot to move or direct a ball depending on the circumstances and what the player wishes to do with the ball. The toe can be used. It's called a toe poke, but because the toe is round and the ball is round, the ball cannot be directed with much accuracy. It's not common to use this, but a coach would never deny a player the option. It's possible to slip a foot between the legs of another player without making contact with that player and touch the ball away just using the toe of the boot. (It's been done, and it's permitted within the laws of the game.) The inside of the foot is most commonly used to move a ball. The fairly flat instep permits a great deal of control in directing a pass or shot. The outstep can be used in the same way, but it is less common. The heel can be used to move a ball. That's frequently referred to as backheeling the ball because it's a tactic generally employed to direct the ball backwards (since you're generally facing the other way). It can be a valuable tool because it is not a common touch and, therefore, comes as a surprise. That's in addition to the fact that it goes backward, and we frequently see defenders (who almost universally set up between a player with a ball and the goal being defended) anticipate that the ball will be released by the controlling player from somewhere in front of his body. Lastly, the use of the top of the foot is a strategy often employed by a player wising extreme power for a shot on goal. The top of the foot is sorta flat, and by choosing to strike the ball with the laces of the boot, the player can get full range of leg motion including the bending of the knee into the action. The fuller the leg motion, the more velocity on the foot and more power on the shot. Oh, and the goalkeeper uses the top of the foot to kick a ball away quite frequently. The skilled player uses all parts of the foot (and most of the rest of his body) to play a ball.