Metaphors are very useful to make a story interesting. They add images, sounds, feelings, ... to a story. This is why they are part of what called "figures of speech".
A metaphor is a comparison between 2 very different things that has some similarity that you want to point out. This similarity is the exact thing you like to say.
There are 2 ways to make a metaphor.
1- Use the verb "is" or "are"
Example: You want to say that George eats a lot. You can say like this (when you talk about his eating habit).
George "is" a pig.
2- Use a very different verb that suggest a similar action so that you actually compare 2 different things.
George runs very fast to the bank of the river.
We need to change the verb "runs" to another verb that is very different but it will suggest some similarity that we want.
George gallops to the bank of the river.
We have compared George to a running horse! So just by changing 1 verb we have been able to create a new image to compare him with a fast animal.
This is why the use of metaphors can make your writing a lot more imaginative and interesting. However it is clear that it is not easy to find the right words to use. One has to have a good English vocab and the imagination to select the right words. One has to practice imaginative thinking in every daily things to be able to do this. This is all about creativity.
Creativity is about trying to be a little different every time when one does the same thing. This helps to find different ways to (perhaps better ways) to get it done. However you must have common sense to know what you can be creative about and what NOT!!! For example, you should not be creative about going down the stairs by jumping down instead of walking! You should not jump off a building when you are supposed to take the stairs! You should not stop addressing your teacher as "Miss, ..." and change to "Woman, ..." if you do not want to get into trouble!