Here are some ways to use it:
* "She's crazy about her new puppy." (Meaning she loves her puppy very much)
* "He's crazy about soccer." (Meaning he is very passionate about soccer)
* "I'm crazy about that new band." (Meaning you are a big fan of the band)
It can also be used to describe someone who is obsessed with something or someone.
Example: "He's crazy about her, he can't stop thinking about her."
Keep in mind that "crazy about" is a very informal expression, so it's best to use it in casual conversations with friends and family.