I need help with the following question about mag. fields and direction.

10. A very long solenoid has n closely wound turns per unit length. The solenoid is wound on a cylinder of radius R, and carries a steady current I. (a) Indicate the direction of the magnetic field inside and outside of the solenoid. Briefly explain how you determined the direction. (b) Sketch the Amperian loop and use Ampere's law ( 5df = 'uoI ) to find the magnetic field inside the solenoid