how to make a magnet coil?

Answer 1

Wrap some copper or aluminum wire around an steel nail.

Attach a DC voltage source (battery).

See link below for a picture.

Notes:
The wire needs to be insulated. For small copper wire this insulation is typically an enamal coating.

Try making three magnets, make two exactly the same with the wire wrapped in the same clockwise direction starting at the nail's head.

On the third magnet, wrap the wire around the bolt/nail in the opposite direction. (counter-clockwire around the nail) The two identical magnets will both have the same North and South poles -- The two nail heads will repell each other. The third magnet has the wire wrapped in the opposite direction and this reverses the magnetic poles. The head of this nail will be attracted to the head of the other two nails.