SPI interface with other board_AVR_ESK1100 or among Arduino itself

[system]

int dat[24] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14};

What is the point of this?

Instead of sending SPDR = 0x01 or, data I was trying to send SPDR = dat[0]; but that also dint work.