After you train a monkey, you have the ability to build a Monkey School. To build a monkey school you need 3 logs 20 branches and 20 stones. At the Monkey School you can train monkeys to carry your stuff.
To train a monkey you need to throw bananas at it.
It can be difficult to see the transport monkey at night, the solution is to give it a random item. When it has an item there will be pink stars around it. You will need 15 bananas and a tamed monkey to make a transport monkey. The best way to throw a banana at a monkey is when it is stuck on a rock, tree, or any other big object.