How to make Full Dublex Communication With PIC

I want to make a RF model car in my project but not only will the remote control
send commands to the car but also the car will send some datas to the screen on the remore control.How can i do that? Can you recommend me useful devices?

Either use two wildly different frequencies, most countries have two suitable ones, or use half duplex - which isn't any good for manual control.

if you're planning to use off-the-shelf radio devices, then simply pick two on different frequencies (usually the cheap ones come in a couple different frequencies) or use ones that are transceivers, and thus are made to be bidirectional. for example, sparkfun.com carries some 2.4GHz transceivers for $15-20 apiece. They're not exactly intended for the kind of long-range, low-cost, low-bandwidth use that you need for RC, but at least it's an option.

If you're planning to build all your own radio electronics, then have fun; it sounds like one of those questions where if you even have to ask, you probably shouldn't be attempting it.