To create a case, you can go to the Cases tab and press "Add New Case".

Then, in the "Add A New Case" dialog, add users that will be associated with this case. Press the "+" or "Invite Members"

Type the name of the user you want to invite in the search bar, and click on the user in the search results.

Next, fill out the required fields of the form. "Case Number" can be left blank. The name of this case will be automatically generated according to the members of this case. "Case Number" is only needed when a case already exists for the users selected, and will be used to differentiate the new case from the existing one.

When you've finished the form, press "Create" to add this new case.