IF you are new to electronics, and from what I get... you are...
That's a more than difficult task... There are many ready solutions which can quickly work with minimum coding and labor....
Solutions list as bluetooth, wifi and mostly forthcoming zigbee...
There are also other RF solutions but most of them would require a encoding and a protocol,
that should be manually hand written in the target MCUs....
I would go for zigbee... numerous choices and available boards from many manufactures....
It's also gentle with the battery... And preferred in battery operated enviroments....
Just google for zigbee modules and you can find pretty much, many modules, from which you can prefer, based on your needs
Best Regards, Lefteris
Greece