A metaphor is a figure of speech that describes an object or action through comparison. Metaphors are great tools to write poems and others types of texts. You are doing a metaphor when you use taken out a word of its traditional context and put it into a new meaning. For example "My heart is a rock"; "My mind is a soap ball poll"; If you want to write very good metaphors free your mind and practice it. Make associations between what you want to describe and things that may be related to your characteristics.