Gravity:The simplest way to power your minecarts is gravity. All you need to do to get a cart going is to set up a section of rails on an incline and set a cart down. However, this is tricky as you cannot control when the cart moves. It can also be inefficient, as the cart will...
Place a block on top of the torch in the lower left corner and place a dispenser beside it (pointing towards the powered rail). Cover up the hole; the two blocks to the right of the dispenser has to be placed above ground or the minecart will get stuck on them. Add some more rails...