One good way to get replies is to tell us what you already wrote. Nobody is going to do your
homework for you, at least not 100%. So start telling us what you did, then what doesn't work,
what you don't understand, etc...
As for starting, if you google for what you want to do I'm sure you will find myriads of source code.
Take one, compile it, run it and tell us what goes wrong.
In addition to Dora's remarks, as short as your "question", I'll give you another tip: Don't use SPI if you need interface 2 boards, but rather UART to do that.