I have red white green and black wires where do they go on my thermostant

A FEW MORE DETAILS PLEASE. Did you remove an old thermostat? What stat are you now trying to wire, brand and model. Some stat take up to 5 wires, all of which enter through the back and connect at a board. https://www.youtube.com/watch?v=-LbWltOCXBU

The guy in that video is a real hack. I only watched a few seconds & saw sparks. He could have blown the transfomer in the furnace just that quick. Be absolutely sure to turn off the switch or breaker to the furnace before working on the thermostat.