Hey Anastasia,
To be honest it is a difficult one. When you're using crave as a verb it is like to desire something strongly. For example, 'to crave attention', ' to crave a cigarette', 'I have a craving for some chocolate cake'.
These are some of the examples I found when you're using 'crave for';
"Most companies and home users crave for a free version of Microsoft Office, due to its capabilities both for study and business"
"When we are attached to things, we are never satisfied and always crave for more and better things"
"We must show the way forward to be the best possible way of achieving the peace and stability we all crave for in that region of Europe"
The way we use it changes a lot depending on the context and whether we are talking about specific stories from the past.
I hope these examples I found help.