Open a crafting table
Place 6 iron ingots in the left and right columns
Place 1 stick in the center slot
Take the 16 rails from the result
Place rails on the ground to make train tracks
Use powered rails if you want trains to move faster
Craft powered rails with 6 gold ingots, 1 stick, and 1 redstone dust
Use redstone torches or redstone power to activate powered rails
Connect rail pieces in a continuous path
Add minecarts to use the tracks