MasterWriteBuf() accepts a pointer to the data to be sent to the I2C interface, while MasterReadBuf() accepts the address of the memory area where the data are going to be stored.
Since the FRam chip needs to know the address where to store and where to read the data to/from the reading is not quite easy.
There is an example project for the FRam as part of the CY8CKIT-044 software. I would suggest you to install the kit files and use the FRam part for your own purposes.
Thank you Bob, I am going to check the sensor hub project :)