First you'll have to connect MOSI/MISO, provide a clock source, and enable the chip.
Then, use the flow chart on page 25 and 26 of the datasheet to retrieve data with a microcontroller. You can easily find Arduino example code for the AD7328 online. Good luck!
I have written code for AD7328 for transmitting data from my controller to ADC using SPI, for that their is chipselect pin in ADC, but I do't understand, how can I read data from AD7328, how should my SPI communication module know when ADC start transmitting data