The frequency and bit user values are determined by design and it will be clear what the correct values to enter are. For some modules, the frequency field is used to input the data rates (UART, EMAC, and so forth). In order to choose appropriate values, you need a good understanding read/write balance, bit switching required estimation, and utilization of the user application. You should also keep in mind the pin multiplexing configuration for the device to avoid enabling mutually exclusive peripherals/configurations at the same time. For available peripherals and the configuration, see the device-specific data manual.