There are a lot of ways to make these and visualize them. I’ve seen them in the form of a spreadsheet or written out in a doc.
I start by writing questions I have about the user. Look at your data and start researching; are they compensating for the lack of this feature in some way? Are there tools that do something similar? Are they using any of them? A job story is a good way to start because you should be thinking about where a user is in your product when they need the feature (or where they are in life when they need your product!).
Don’t be afraid to ask your users and do some preliminary research either. Send a survey or email, get to know the problem they face and why your feature/tool/product will help.
Lastly, put yourself in your users’ shoes. It can be hard to detach yourself from what you know about your product, but it can be a helpful guide at the very least.