The old thermostat only has 2 wires (red,white) and rhe new one has 4 (red,white, green, and yellow) what do i do ?

No AC? You simply connect your red to red on the stat and white to white and that should be it. The other wires you don't need so remove or cap them (I assume you meant connections and not wires with the new tstat). You also didn't supply the name and model for the new tstat but same principle applies in this video.

https://www.youtube.com/watch?v=wMu7L7pVFak