The Custom Fields module allows you to assign any value to custom fields defined in the Custom Fields Settings module.
The Custom Fields module is available by default to administrators and team leaders, but this can be changed (please read the related documentation in the Custom Fields Settings section)
Simply type a value in the field.
The value is automatically saved.
When typing your value, you will note that an auto-suggest window will appear.
The auto-suggest will show you the values already used previously in the field and will help you keep your data clean, avoiding duplicates.
All custom fields can be used as a new column in any of your table report.
Following the given instructions in the Reports module documentation, add a new column and pick the custom field you need.
The custom field will now appear as a new column in your report.
Custom fields can also be used as filters in the reports.
Just access the parameters of the report clicking on "Change this report" and go to the filters area.
Here again, please refer to the Report module documentation to further read about filters in reports.