The term Resources is used in Celoxis to indicate any person, role, equipment or facility that would be required for completion of the project activity. Users is another term used for Resources. Before you start using Celoxis, you have to define your Users. These can be the people who you have invited to join in your evaluation. Or you can create more Users(resources) which are your virtual users i.e without a login/password. For example, you need use of some Lab for performing your tasks and you need to allocate it for use against specific tasks. You can create a User called Lab without a userid/password.
To create users, please read the Add/Edit Users section of the User Guide. After creating your project and defining your tasks, you can read about Resource Assignment.
A sample CSV file attached for your reference.